diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationCell.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationCell.tsx
index d315b5c..5bcfdb2 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationCell.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationCell.tsx
@@ -11,7 +11,6 @@ import InputCell from './cells/InputCell'
 import SelectCell from './cells/SelectCell'
 import MultiSelectCell from './cells/MultiSelectCell'
 import { TableCell } from '@/components/ui/table'
-import { Skeleton } from '@/components/ui/skeleton'
 
 // Context for copy down selection mode
 export const CopyDownContext = React.createContext<{
@@ -80,7 +79,8 @@ const BaseCellContent = React.memo(({
   className = '',
   fieldKey = '',
   onStartEdit,
-  onEndEdit
+  onEndEdit,
+  isValidating
 }: {
   field: Field<string>;
   value: any;
@@ -91,6 +91,7 @@ const BaseCellContent = React.memo(({
   fieldKey?: string;
   onStartEdit?: () => void;
   onEndEdit?: () => void;
+  isValidating?: boolean;
 }) => {
   // Get field type information
   const fieldType = fieldKey === 'line' || fieldKey === 'subline' 
@@ -123,6 +124,7 @@ const BaseCellContent = React.memo(({
         hasErrors={hasErrors}
         className={className}
         disabled={field.disabled}
+        isValidating={isValidating}
       />
     );
   }
@@ -139,6 +141,7 @@ const BaseCellContent = React.memo(({
         hasErrors={hasErrors}
         className={className}
         disabled={field.disabled}
+        isValidating={isValidating}
       />
     );
   }
@@ -155,6 +158,7 @@ const BaseCellContent = React.memo(({
         hasErrors={hasErrors}
         className={className}
         disabled={field.disabled}
+        isValidating={isValidating}
       />
     );
   }
@@ -170,6 +174,7 @@ const BaseCellContent = React.memo(({
       isMultiline={isMultiline}
       isPrice={isPrice}
       disabled={field.disabled}
+      isValidating={isValidating}
     />
   );
 }, (prev, next) => {
@@ -466,35 +471,33 @@ const ValidationCell = React.memo(({
             </TooltipProvider>
           </div>
         )}
-        {isLoading ? (
-          <div className={`flex items-center justify-center gap-2 border ${hasError || isRequiredButEmpty ? 'border-red-500' : 'border-input'} rounded-md px-2 py-2`}>
-            <Skeleton className="w-full h-4" />
-          </div>
-        ) : (
-          <div 
-            className={`truncate overflow-hidden ${isCopyDownHovered && !copyDownContext.isInCopyDownMode ? 'bg-blue-50/50' : ''}`}
-            style={{
-              backgroundColor: isSourceCell ? '#dbeafe' : 
-                              isSelectedTarget ? '#bfdbfe' : 
-                              isInTargetRow && isTargetRowHovered ? '#dbeafe' : 
-                              undefined,
-              borderRadius: (isSourceCell || isSelectedTarget || isInTargetRow) ? '0.375rem' : undefined,
-              boxShadow: isSourceCell ? '0 0 0 2px #3b82f6' : undefined
-            }}
-          >
-            <BaseCellContent
-              field={field}
-              value={displayValue}
-              onChange={onChange}
-              hasErrors={hasError || isRequiredButEmpty}
-              options={options}
-              className={cellClassName}
-              fieldKey={fieldKey}
-              onStartEdit={handleStartEdit}
-              onEndEdit={handleEndEdit}
-            />
-          </div>
-        )}
+        <div 
+          className={`relative truncate overflow-hidden ${isCopyDownHovered && !copyDownContext.isInCopyDownMode ? 'bg-blue-50/50' : ''}`}
+          style={{
+            backgroundColor: isSourceCell ? '#dbeafe' : 
+                            isSelectedTarget ? '#bfdbfe' : 
+                            isInTargetRow && isTargetRowHovered ? '#dbeafe' : 
+                            undefined,
+            borderRadius: (isSourceCell || isSelectedTarget || isInTargetRow) ? '0.375rem' : undefined,
+            boxShadow: isSourceCell ? '0 0 0 2px #3b82f6' : undefined
+          }}
+        >
+          <BaseCellContent
+            field={field}
+            value={displayValue}
+            onChange={onChange}
+            hasErrors={hasError || isRequiredButEmpty}
+            options={options}
+            className={cellClassName}
+            fieldKey={fieldKey}
+            onStartEdit={handleStartEdit}
+            onEndEdit={handleEndEdit}
+            isValidating={isLoading}
+          />
+          {isLoading && (
+            <span className="pointer-events-none absolute right-2 top-2 h-2 w-2 rounded-full bg-muted-foreground animate-pulse" />
+          )}
+        </div>
       </div>
     </TableCell>
   );
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationTable.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationTable.tsx
index 73caad1..144715b 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationTable.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/components/ValidationTable.tsx
@@ -1,4 +1,4 @@
-import React, { useMemo, useCallback, useState } from 'react'
+import React, { useMemo, useCallback, useState, useEffect, useRef } from 'react'
 import { 
   useReactTable, 
   getCoreRowModel, 
@@ -6,6 +6,7 @@ import {
   RowSelectionState,
   ColumnDef
 } from '@tanstack/react-table'
+import { useVirtualizer } from '@tanstack/react-virtual'
 import { Fields, Field } from '../../../types'
 import { RowData, Template } from '../hooks/validationTypes'
 import ValidationCell, { CopyDownContext } from './ValidationCell'
@@ -193,6 +194,14 @@ const ValidationTable = <T extends string>({
   upcValidationResults
 }: ValidationTableProps<T>) => {
   const { translations } = useRsi<T>();
+  const tableRootRef = useRef<HTMLDivElement | null>(null);
+  const getScrollElement = useCallback(() => tableRootRef.current?.parentElement ?? null, []);
+  const [, forceRerender] = useState(0);
+
+  useEffect(() => {
+    if (!tableRootRef.current) return;
+    forceRerender((value) => value + 1);
+  }, []);
 
   // Add state for copy down selection mode
   const [isInCopyDownMode, setIsInCopyDownMode] = useState(false);
@@ -392,7 +401,10 @@ const ValidationTable = <T extends string>({
         } else if (fieldKey === 'subline' && rowId && rowSublines[rowId]) {
           options = rowSublines[rowId];
         }
-        
+
+        const validatingKey = `${row.index}-${fieldKey}`;
+        const isCellValidating = validatingCells.has(validatingKey);
+
         // Get the current cell value first
         const currentValue = fieldKey === 'item_number' && row.original[field.key] 
                            ? row.original[field.key] 
@@ -471,7 +483,7 @@ const ValidationTable = <T extends string>({
             value={currentValue}
             onChange={(value) => handleFieldUpdate(row.index, field.key as T, value)}
             errors={cellErrors}
-            isValidating={isLoading}
+            isValidating={isLoading || isCellValidating}
             fieldKey={fieldKey}
             options={options}
             itemNumber={itemNumber}
@@ -505,6 +517,47 @@ const ValidationTable = <T extends string>({
     getRowId: useCallback((_row: RowData<T>, index: number) => String(index), []),
   });
 
+  const rowModel = table.getRowModel();
+  const rows = rowModel.rows;
+  const visibleColumnCount = table.getVisibleFlatColumns().length;
+
+  const rowVirtualizer = useVirtualizer({
+    count: rows.length,
+    getScrollElement,
+    estimateSize: () => 66,
+    overscan: 8,
+    measureElement:
+      typeof window !== 'undefined'
+        ? (el: Element | null) => el?.getBoundingClientRect().height || 0
+        : undefined,
+  });
+
+  const scrollElement = getScrollElement();
+
+  const virtualRows = scrollElement
+    ? rowVirtualizer.getVirtualItems()
+    : rows.map((_, index) => ({
+        index,
+        key: `row-fallback-${index}`,
+        start: 0,
+        end: 0,
+        size: 0,
+      }));
+  const paddingTop = scrollElement && virtualRows.length > 0 ? virtualRows[0].start : 0;
+  const paddingBottom =
+    scrollElement && virtualRows.length > 0
+      ? rowVirtualizer.getTotalSize() - virtualRows[virtualRows.length - 1].end
+      : 0;
+
+  const measureVirtualRow = useCallback(
+    (node: HTMLTableRowElement | null) => {
+      const scrollEl = getScrollElement();
+      if (!scrollEl || !node) return;
+      rowVirtualizer.measureElement(node);
+    },
+    [getScrollElement, rowVirtualizer]
+  );
+
   // Calculate total table width for stable horizontal scrolling
   const totalWidth = useMemo(() => {
     return columns.reduce((total, col) => total + (col.size || 0), 0);
@@ -525,7 +578,7 @@ const ValidationTable = <T extends string>({
 
   return (
     <CopyDownContext.Provider value={copyDownContextValue}>
-      <div className="min-w-max relative">
+      <div ref={tableRootRef} className="min-w-max relative">
         {/* Add global styles for copy down mode */}
         {isInCopyDownMode && (
           <style>
@@ -630,7 +683,17 @@ const ValidationTable = <T extends string>({
             transform: 'translateZ(0)' // Force GPU acceleration
           }}>
             <TableBody>
-              {table.getRowModel().rows.map((row) => {
+              {paddingTop > 0 && (
+                <TableRow key="virtual-padding-top">
+                  <TableCell
+                    colSpan={visibleColumnCount}
+                    style={{ height: `${paddingTop}px`, padding: 0, border: 'none' }}
+                  />
+                </TableRow>
+              )}
+              {virtualRows.map((virtualRow) => {
+                const row = rows[virtualRow.index];
+                if (!row) return null;
                 // Precompute validation error status for this row
                 const hasErrors = validationErrors.has(parseInt(row.id)) && 
                                 Object.keys(validationErrors.get(parseInt(row.id)) || {}).length > 0;
@@ -659,6 +722,7 @@ const ValidationTable = <T extends string>({
                       isCopyDownTarget ? "cursor-pointer copy-down-target-row" : ""
                     )}
                     style={rowStyle}
+                    ref={scrollElement ? measureVirtualRow : undefined}
                     onMouseEnter={() => handleRowMouseEnter(parseInt(row.id))}
                   >
                     {row.getVisibleCells().map((cell: any) => (
@@ -669,6 +733,14 @@ const ValidationTable = <T extends string>({
                   </TableRow>
                 );
               })}
+              {paddingBottom > 0 && (
+                <TableRow key="virtual-padding-bottom">
+                  <TableCell
+                    colSpan={visibleColumnCount}
+                    style={{ height: `${paddingBottom}px`, padding: 0, border: 'none' }}
+                  />
+                </TableRow>
+              )}
             </TableBody>
           </Table>
         </div>
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/InputCell.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/InputCell.tsx
index 353f9fa..0e247bf 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/InputCell.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/InputCell.tsx
@@ -1,4 +1,4 @@
-import React, { useState, useCallback, useMemo } from 'react'
+import React, { useState, useCallback, useMemo, useEffect } from 'react'
 import { Field } from '../../../../types'
 import { Input } from '@/components/ui/input'
 import { cn } from '@/lib/utils'
@@ -15,8 +15,10 @@ interface InputCellProps<T extends string> {
   isPrice?: boolean
   disabled?: boolean
   className?: string
+  isValidating?: boolean
 }
 
+
 // (removed unused formatPrice helper)
 
 const InputCell = <T extends string>({
@@ -29,11 +31,12 @@ const InputCell = <T extends string>({
   isMultiline = false,
   isPrice = false,
   disabled = false,
-  className = ''
+  className = '', isValidating: _isValidating = false
 }: InputCellProps<T>) => {
   const [isEditing, setIsEditing] = useState(false);
   const [editValue, setEditValue] = useState('');
   const [isHovered, setIsHovered] = useState(false);
+  const [pendingDisplayValue, setPendingDisplayValue] = useState<string | null>(null);
   
   // Remove optimistic updates and rely on parent state
   
@@ -48,6 +51,7 @@ const InputCell = <T extends string>({
   // Handle focus event
   const handleFocus = useCallback(() => {
     setIsEditing(true);
+    setPendingDisplayValue(null);
     
     if (value !== undefined && value !== null) {
       if (isPrice) {
@@ -67,6 +71,8 @@ const InputCell = <T extends string>({
   // Handle blur event - save to parent only
   const handleBlur = useCallback(() => {
     const finalValue = editValue.trim();
+
+    setPendingDisplayValue(finalValue);
     
     // Save to parent - parent must update immediately for this to work
     onChange(finalValue);
@@ -81,23 +87,29 @@ const InputCell = <T extends string>({
     const newValue = isPrice ? e.target.value.replace(/[$,]/g, '') : e.target.value;
     setEditValue(newValue);
   }, [isPrice]);
-  
-  // Get the display value - use parent value directly
-  const displayValue = useMemo(() => {
+
+  useEffect(() => {
+    if (pendingDisplayValue === null) return;
     const currentValue = value ?? '';
-    
-    // Handle price formatting for display
-    if (isPrice && currentValue !== '' && currentValue !== undefined && currentValue !== null) {
-      if (typeof currentValue === 'number') {
-        return currentValue.toFixed(2);
-      } else if (typeof currentValue === 'string' && /^-?\d+(\.\d+)?$/.test(currentValue)) {
-        return parseFloat(currentValue).toFixed(2);
+    if (String(currentValue) === pendingDisplayValue) {
+      setPendingDisplayValue(null);
+    }
+  }, [value, pendingDisplayValue]);
+  
+  // Get the display value - prefer pending value when present for immediate feedback
+  const displayValue = useMemo(() => {
+    const rawValue = pendingDisplayValue !== null ? pendingDisplayValue : value ?? '';
+
+    if (isPrice && rawValue !== '' && rawValue !== undefined && rawValue !== null) {
+      if (typeof rawValue === 'number') {
+        return rawValue.toFixed(2);
+      } else if (typeof rawValue === 'string' && /^-?\d+(\.\d+)?$/.test(rawValue)) {
+        return parseFloat(rawValue).toFixed(2);
       }
     }
-    
-    // For non-price or invalid price values, return as-is
-    return String(currentValue);
-  }, [isPrice, value]);
+
+    return String(rawValue);
+  }, [isPrice, value, pendingDisplayValue]);
   
   // Add outline even when not in focus
   const outlineClass = "border focus-visible:ring-0 focus-visible:ring-offset-0";
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/MultiSelectCell.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/MultiSelectCell.tsx
index c83b57b..62a0a4d 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/MultiSelectCell.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/MultiSelectCell.tsx
@@ -24,8 +24,10 @@ interface MultiSelectCellProps<T extends string> {
   options?: readonly FieldOption[]
   disabled?: boolean
   className?: string
+  isValidating?: boolean
 }
 
+
 // Memoized option item to prevent unnecessary renders for large option lists
 const OptionItem = React.memo(({
   option,
@@ -158,7 +160,7 @@ const MultiSelectCell = <T extends string>({
   hasErrors,
   options: providedOptions,
   disabled = false,
-  className = ''
+  className = '', isValidating: _isValidating = false
 }: MultiSelectCellProps<T>) => {
   const [open, setOpen] = useState(false)
   const [searchQuery, setSearchQuery] = useState("")
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/SelectCell.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/SelectCell.tsx
index 6fcd875..5aebd34 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/SelectCell.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/components/cells/SelectCell.tsx
@@ -22,8 +22,10 @@ interface SelectCellProps<T extends string> {
   options: readonly any[]
   disabled?: boolean
   className?: string
+  isValidating?: boolean
 }
 
+
 // Lightweight version of the select cell with minimal dependencies
 const SelectCell = <T extends string>({
   field,
@@ -34,7 +36,7 @@ const SelectCell = <T extends string>({
   hasErrors,
   options = [],
   disabled = false,
-  className = ''
+  className = '', isValidating = false
 }: SelectCellProps<T>) => {
   // State for the open/closed state of the dropdown
   const [open, setOpen] = useState(false);
@@ -47,6 +49,7 @@ const SelectCell = <T extends string>({
   
   // State to track if the value is being processed/validated
   const [isProcessing, setIsProcessing] = useState(false);
+  const showProcessing = isProcessing || isValidating;
   
   // Add state for hover
   const [isHovered, setIsHovered] = useState(false);
@@ -61,8 +64,10 @@ const SelectCell = <T extends string>({
   useEffect(() => {
     setInternalValue(value);
     // When the value prop changes, it means validation is complete
-    setIsProcessing(false);
-  }, [value]);
+    if (!isValidating) {
+      setIsProcessing(false);
+    }
+  }, [value, isValidating]);
   
   // Memoize options processing to avoid recalculation on every render
   const selectOptions = useMemo(() => {
@@ -144,7 +149,9 @@ const SelectCell = <T extends string>({
     
     // 6. Clear processing state after a short delay - reduced for responsiveness
     setTimeout(() => {
+      if (!isValidating) {
       setIsProcessing(false);
+    }
     }, 50);
   }, [onChange, onEndEdit]);
 
@@ -200,7 +207,7 @@ const SelectCell = <T extends string>({
             "w-full justify-between font-normal",
             "border",
             !internalValue && "text-muted-foreground",
-            isProcessing && "text-muted-foreground",
+            showProcessing && "text-muted-foreground",
             hasErrors ? "border-destructive" : "",
             className
           )}
@@ -233,7 +240,7 @@ const SelectCell = <T extends string>({
           onMouseEnter={() => setIsHovered(true)}
           onMouseLeave={() => setIsHovered(false)}
         >
-          <span className={isProcessing ? "opacity-70" : ""}>
+          <span className={showProcessing ? "opacity-70" : ""}>
             {displayValue}
           </span>
           <ChevronsUpDown className="mr-1.5 h-4 w-4 shrink-0 opacity-50" />
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useRowOperations.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useRowOperations.tsx
index 62d8c20..5dbd926 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useRowOperations.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useRowOperations.tsx
@@ -1,21 +1,100 @@
-import { useCallback, useMemo } from 'react';
-import { RowData } from './validationTypes';
+import { useCallback, useEffect, useMemo, useRef, startTransition } from 'react';
+import type { Dispatch, SetStateAction } from 'react';
+import { RowData, isEmpty as isValueEmpty } from './validationTypes';
 import type { Field, Fields } from '../../../types';
 import { ErrorSources, ErrorType, ValidationError } from '../../../types';
 import { useUniqueValidation } from './useUniqueValidation';
-import { isEmpty } from './validationTypes';
 
 export const useRowOperations = <T extends string>(
   data: RowData<T>[],
   fields: Fields<T>,
   setData: React.Dispatch<React.SetStateAction<RowData<T>[]>>,
   setValidationErrors: React.Dispatch<React.SetStateAction<Map<number, Record<string, ValidationError[]>>>>,
-  validateFieldFromHook: (value: any, field: Field<T>) => ValidationError[]
+  validateFieldFromHook: (value: any, field: Field<T>) => ValidationError[],
+  setValidatingCells?: Dispatch<SetStateAction<Set<string>>>
 ) => {
-  // Uniqueness validation utilities
   const { validateUniqueField } = useUniqueValidation<T>(fields);
 
-  // Determine which field keys are considered uniqueness-constrained
+  const dataRef = useRef(data);
+  useEffect(() => {
+    dataRef.current = data;
+  }, [data]);
+
+  type ValidationTask = { cancel: () => void };
+  const pendingValidationTasksRef = useRef<Map<string, ValidationTask>>(new Map());
+
+  const scheduleIdleTask = useCallback((taskKey: string, runTask: () => void) => {
+    const existingTask = pendingValidationTasksRef.current.get(taskKey);
+    existingTask?.cancel();
+
+    const execute = () => {
+      pendingValidationTasksRef.current.delete(taskKey);
+      runTask();
+    };
+
+    if (typeof window !== 'undefined') {
+      const win = window as Window & typeof globalThis & {
+        requestIdleCallback?: (callback: IdleRequestCallback, options?: IdleRequestOptions) => number;
+        cancelIdleCallback?: (handle: number) => void;
+      };
+
+      if (win.requestIdleCallback) {
+        const handle = win.requestIdleCallback(() => {
+          execute();
+        }, { timeout: 250 });
+
+        pendingValidationTasksRef.current.set(taskKey, {
+          cancel: () => win.cancelIdleCallback?.(handle),
+        });
+        return;
+      }
+
+      const timeoutId = window.setTimeout(execute, 0);
+      pendingValidationTasksRef.current.set(taskKey, {
+        cancel: () => window.clearTimeout(timeoutId),
+      });
+      return;
+    }
+
+    execute();
+  }, []);
+
+  const updateValidatingCell = useCallback(
+    (rowIndex: number, fieldKey: string, pending: boolean) => {
+      if (!setValidatingCells) return;
+      const cellKey = `${rowIndex}-${fieldKey}`;
+      setValidatingCells((prev: Set<string>) => {
+        const hasKey = prev.has(cellKey);
+        if (pending && hasKey) return prev;
+        if (!pending && !hasKey) return prev;
+        const next = new Set(prev);
+        if (pending) next.add(cellKey);
+        else next.delete(cellKey);
+        return next;
+      });
+    },
+    [setValidatingCells]
+  );
+
+  const scheduleFieldValidation = useCallback(
+    (rowIndex: number, fieldKey: string, runValidation: () => void) => {
+      updateValidatingCell(rowIndex, fieldKey, true);
+      try {
+        runValidation();
+      } finally {
+        updateValidatingCell(rowIndex, fieldKey, false);
+      }
+    },
+    [updateValidatingCell]
+  );
+
+  useEffect(() => {
+    return () => {
+      pendingValidationTasksRef.current.forEach((task) => task.cancel());
+      pendingValidationTasksRef.current.clear();
+    };
+  }, []);
+
   const uniquenessFieldKeys = useMemo(() => {
     const keys = new Set<string>([
       'item_number',
@@ -25,15 +104,16 @@ export const useRowOperations = <T extends string>(
       'notions_no',
       'name'
     ]);
-    fields.forEach((f) => {
-      if (f.validations?.some((v) => v.rule === 'unique')) {
-        keys.add(String(f.key));
+
+    fields.forEach((field) => {
+      if (field.validations?.some((v) => v.rule === 'unique')) {
+        keys.add(String(field.key));
       }
     });
+
     return keys;
   }, [fields]);
 
-  // Merge per-field uniqueness errors into the validation error map
   const mergeUniqueErrorsForFields = useCallback(
     (
       baseErrors: Map<number, Record<string, ValidationError[]>>,
@@ -44,26 +124,19 @@ export const useRowOperations = <T extends string>(
 
       const newErrors = new Map(baseErrors);
 
-      // For each field, compute duplicates and merge
       fieldKeysToCheck.forEach((fieldKey) => {
         if (!uniquenessFieldKeys.has(fieldKey)) return;
 
-        // Compute unique errors for this single field
         const uniqueMap = validateUniqueField(dataForCalc, fieldKey);
-
-        // Rows that currently have uniqueness errors for this field
         const rowsWithUniqueErrors = new Set<number>();
         uniqueMap.forEach((_, rowIdx) => rowsWithUniqueErrors.add(rowIdx));
 
-        // First, apply/overwrite unique errors for rows that have duplicates
         uniqueMap.forEach((errorsForRow, rowIdx) => {
           const existing = { ...(newErrors.get(rowIdx) || {}) };
-
-          // Convert InfoWithSource to ValidationError[] for this field
           const info = errorsForRow[fieldKey];
-          // Only apply uniqueness error when the value is non-empty
           const currentValue = (dataForCalc[rowIdx] as any)?.[fieldKey];
-          if (info && !isEmpty(currentValue)) {
+
+          if (info && !isValueEmpty(currentValue)) {
             existing[fieldKey] = [
               {
                 message: info.message,
@@ -78,9 +151,7 @@ export const useRowOperations = <T extends string>(
           else newErrors.delete(rowIdx);
         });
 
-        // Then, remove any stale unique errors for this field where duplicates are resolved
         newErrors.forEach((rowErrs, rowIdx) => {
-          // Skip rows that still have unique errors for this field
           if (rowsWithUniqueErrors.has(rowIdx)) return;
 
           if ((rowErrs as any)[fieldKey]) {
@@ -99,361 +170,372 @@ export const useRowOperations = <T extends string>(
     [uniquenessFieldKeys, validateUniqueField]
   );
 
-  // Helper function to validate a field value
+  const pendingUniqueFieldsRef = useRef<Set<string>>(new Set());
+
+  const runUniqueValidation = useCallback(
+    (fieldsToProcess: string[]) => {
+      if (!fieldsToProcess.length) return;
+      setValidationErrors((prev) =>
+        mergeUniqueErrorsForFields(prev, dataRef.current, fieldsToProcess)
+      );
+    },
+    [mergeUniqueErrorsForFields, setValidationErrors]
+  );
+
+  const scheduleUniqueValidation = useCallback(
+    (fieldKeys: string[]) => {
+      if (!fieldKeys.length) return;
+      const uniqueKeys = fieldKeys.filter((key) => uniquenessFieldKeys.has(key));
+      if (!uniqueKeys.length) return;
+
+      if (pendingUniqueFieldsRef.current.size === 0 && uniqueKeys.length <= 2) {
+        const immediateKeys = Array.from(new Set(uniqueKeys));
+        runUniqueValidation(immediateKeys);
+        return;
+      }
+
+      uniqueKeys.forEach((fieldKey) => pendingUniqueFieldsRef.current.add(fieldKey));
+
+      scheduleIdleTask('unique:batch', () => {
+        const fieldsToProcess = Array.from(pendingUniqueFieldsRef.current);
+        pendingUniqueFieldsRef.current.clear();
+        if (!fieldsToProcess.length) return;
+        runUniqueValidation(fieldsToProcess);
+      });
+    },
+    [runUniqueValidation, scheduleIdleTask, uniquenessFieldKeys]
+  );
+
   const fieldValidationHelper = useCallback(
     (rowIndex: number, specificField?: string) => {
-      // Skip validation if row doesn't exist
-      if (rowIndex < 0 || rowIndex >= data.length) return;
+      const currentData = dataRef.current;
+      if (rowIndex < 0 || rowIndex >= currentData.length) return;
 
-      // Get the row data
-      const row = data[rowIndex];
+     const row = currentData[rowIndex];
 
-      // If validating a specific field, only check that field
       if (specificField) {
         const field = fields.find((f) => String(f.key) === specificField);
-        if (field) {
-          const value = row[specificField as keyof typeof row];
+        if (!field) return;
 
-          // Use state setter instead of direct mutation
-          setValidationErrors((prev) => {
-            let newErrors = new Map(prev);
-            const existingErrors = { ...(newErrors.get(rowIndex) || {}) };
+        const value = row[specificField as keyof typeof row];
 
-            // Quick check for required fields - this prevents flashing errors
-            const isRequired = field.validations?.some(
-              (v) => v.rule === "required"
-            );
-            const isEmpty =
-              value === undefined ||
-              value === null ||
-              value === "" ||
-              (Array.isArray(value) && value.length === 0) ||
-              (typeof value === "object" &&
-                value !== null &&
-                Object.keys(value).length === 0);
-
-            // For non-empty values, remove required errors immediately
-            if (isRequired && !isEmpty && existingErrors[specificField]) {
-              const nonRequiredErrors = existingErrors[specificField].filter(
-                (e) => e.type !== ErrorType.Required
-              );
-              if (nonRequiredErrors.length === 0) {
-                // If no other errors, remove the field entirely from errors
-                delete existingErrors[specificField];
-              } else {
-                existingErrors[specificField] = nonRequiredErrors;
-              }
-            }
-
-            // Run full validation for the field
-            const errors = validateFieldFromHook(value, field as unknown as Field<T>);
-
-            // Update validation errors for this field
-            if (errors.length > 0) {
-              existingErrors[specificField] = errors;
-            } else {
-              delete existingErrors[specificField];
-            }
-
-            // Update validation errors map
-            if (Object.keys(existingErrors).length > 0) {
-              newErrors.set(rowIndex, existingErrors);
-            } else {
-              newErrors.delete(rowIndex);
-            }
-
-            // If field is uniqueness-constrained, also re-validate uniqueness for the column
-            if (uniquenessFieldKeys.has(specificField)) {
-              const dataForCalc = data; // latest data
-              newErrors = mergeUniqueErrorsForFields(newErrors, dataForCalc, [specificField]);
-            }
-
-            return newErrors;
-          });
-        }
-      } else {
-        // Validate all fields in the row
+        updateValidatingCell(rowIndex, specificField, true);
         setValidationErrors((prev) => {
-          const newErrors = new Map(prev);
-          const rowErrors: Record<string, ValidationError[]> = {};
+          const existingErrors = prev.get(rowIndex) || {};
+          const newRowErrors = { ...existingErrors };
+          let rowChanged = false;
 
-          fields.forEach((field) => {
+          const isRequired = field.validations?.some((v) => v.rule === 'required');
+          const valueIsEmpty =
+            value === undefined ||
+            value === null ||
+            value === '' ||
+            (Array.isArray(value) && value.length === 0) ||
+            (typeof value === 'object' && value !== null && Object.keys(value).length === 0);
+
+          if (isRequired && !valueIsEmpty && newRowErrors[specificField]) {
+            const nonRequiredErrors = newRowErrors[specificField].filter((e) => e.type !== ErrorType.Required);
+
+            if (nonRequiredErrors.length === 0) {
+              rowChanged = true;
+              delete newRowErrors[specificField];
+            } else if (nonRequiredErrors.length !== newRowErrors[specificField].length) {
+              rowChanged = true;
+              newRowErrors[specificField] = nonRequiredErrors;
+            }
+          }
+
+          const errors = validateFieldFromHook(value, field as unknown as Field<T>);
+
+          if (errors.length > 0) {
+            const existing = newRowErrors[specificField] || [];
+            const sameLength = existing.length === errors.length;
+            const sameContent = sameLength && existing.every((err, idx) => err.message === errors[idx].message && err.type === errors[idx].type);
+            if (!sameContent) {
+              rowChanged = true;
+              newRowErrors[specificField] = errors;
+            }
+          } else if (newRowErrors[specificField]) {
+            rowChanged = true;
+            delete newRowErrors[specificField];
+          }
+
+          let resultMap = prev;
+          if (rowChanged) {
+            resultMap = new Map(prev);
+            if (Object.keys(newRowErrors).length > 0) {
+              resultMap.set(rowIndex, newRowErrors);
+            } else {
+              resultMap.delete(rowIndex);
+            }
+          }
+
+          if (uniquenessFieldKeys.has(specificField)) {
+            scheduleUniqueValidation([specificField]);
+            return rowChanged ? resultMap : prev;
+          }
+
+          return rowChanged ? resultMap : prev;
+        });
+        updateValidatingCell(rowIndex, specificField, false);
+      } else {
+        setValidationErrors((prev) => {
+            const rowErrors: Record<string, ValidationError[]> = {};
+
+            fields.forEach((field) => {
             const fieldKey = String(field.key);
-            const value = row[fieldKey as keyof typeof row];
-            const errors = validateFieldFromHook(value, field as unknown as Field<T>);
-
+            const valueForField = row[fieldKey as keyof typeof row];
+            const errors = validateFieldFromHook(valueForField, field as unknown as Field<T>);
             if (errors.length > 0) {
               rowErrors[fieldKey] = errors;
             }
           });
 
-          // Update validation errors map
-          if (Object.keys(rowErrors).length > 0) {
-            newErrors.set(rowIndex, rowErrors);
-          } else {
-            newErrors.delete(rowIndex);
+          if (Object.keys(rowErrors).length === 0) {
+            if (!prev.has(rowIndex)) return prev;
+            const result = new Map(prev);
+            result.delete(rowIndex);
+            return result;
           }
 
-          return newErrors;
-        });
+          const existing = prev.get(rowIndex);
+          const sameEntries = existing && Object.keys(rowErrors).length === Object.keys(existing).length && Object.entries(rowErrors).every(([key, val]) => {
+            const existingVal = existing[key];
+            return (
+              existingVal &&
+              existingVal.length === val.length &&
+              existingVal.every((err, idx) => err.message === val[idx].message && err.type === val[idx].type)
+            );
+          });
+
+          if (sameEntries) return prev;
+
+          const result = new Map(prev);
+          result.set(rowIndex, rowErrors);
+          return result;
+          });
+        const uniqueKeys = fields
+          .map((field) => String(field.key))
+          .filter((fieldKey) => uniquenessFieldKeys.has(fieldKey));
+        if (uniqueKeys.length > 0) {
+          scheduleUniqueValidation(uniqueKeys);
+        }
       }
     },
-    [data, fields, validateFieldFromHook, setValidationErrors, mergeUniqueErrorsForFields, uniquenessFieldKeys]
+    [fields, scheduleUniqueValidation, setValidationErrors, uniquenessFieldKeys, validateFieldFromHook]
   );
 
-  // Use validateRow as an alias for fieldValidationHelper for compatibility
   const validateRow = fieldValidationHelper;
 
-  // Modified updateRow function that properly handles field-specific validation
   const updateRow = useCallback(
     (rowIndex: number, key: T, value: any) => {
-      // Process value before updating data
       let processedValue = value;
 
-      // Strip dollar signs from price fields
-      if (
-        (key === "msrp" || key === "cost_each") &&
-        typeof value === "string"
-      ) {
-        processedValue = value.replace(/[$,]/g, "");
-
-        // Also ensure it's a valid number
+      if ((key === 'msrp' || key === 'cost_each') && typeof value === 'string') {
+        processedValue = value.replace(/[$,]/g, '');
         const numValue = parseFloat(processedValue);
-        if (!isNaN(numValue)) {
+        if (!Number.isNaN(numValue)) {
           processedValue = numValue.toFixed(2);
         }
       }
 
-      // Find the row data first
-      const rowData = data[rowIndex];
+      const currentData = dataRef.current;
+      const rowData = currentData[rowIndex];
       if (!rowData) {
         console.error(`No row data found for index ${rowIndex}`);
         return;
       }
 
-      // Create a copy of the row to avoid mutation
       const updatedRow = { ...rowData, [key]: processedValue };
 
-      // Update the data immediately - this sets the value
-      setData((prevData) => {
-        const newData = [...prevData];
-        if (rowIndex >= 0 && rowIndex < newData.length) {
-          newData[rowIndex] = updatedRow;
-        }
-        return newData;
+      const nextData = [...currentData];
+      if (rowIndex >= 0 && rowIndex < nextData.length) {
+        nextData[rowIndex] = updatedRow;
+      }
+      dataRef.current = nextData;
+
+      startTransition(() => {
+        setData(() => nextData);
       });
 
-      // Find the field definition
       const field = fields.find((f) => String(f.key) === key);
       if (!field) return;
 
-      // CRITICAL FIX: Combine both validation operations into a single state update
-      // to prevent intermediate rendering that causes error icon flashing
-      setValidationErrors((prev) => {
-        // Start with previous errors
-        let newMap = new Map(prev);
-        const existingErrors = newMap.get(rowIndex) || {};
-        const newRowErrors = { ...existingErrors };
+      scheduleFieldValidation(rowIndex, String(key), () => {
+        setValidationErrors((prev) => {
+            const existingErrors = prev.get(rowIndex) || {};
+            const newRowErrors = { ...existingErrors };
+            let rowChanged = false;
 
-        // Check for required field first
-        const isRequired = field.validations?.some(
-          (v) => v.rule === "required"
-        );
-        const isEmpty =
-          processedValue === undefined ||
-          processedValue === null ||
-          processedValue === "" ||
-          (Array.isArray(processedValue) && processedValue.length === 0) ||
-          (typeof processedValue === "object" &&
-            processedValue !== null &&
-            Object.keys(processedValue).length === 0);
+          const latestRow = dataRef.current[rowIndex];
+          const currentValue = latestRow ? (latestRow[String(key) as keyof typeof latestRow] as unknown) : processedValue;
 
-        // For required fields with values, remove required errors
-        if (isRequired && !isEmpty && newRowErrors[key as string]) {
-          const hasRequiredError = newRowErrors[key as string].some(
-            (e) => e.type === ErrorType.Required
-          );
-
-          if (hasRequiredError) {
-            // Remove required errors but keep other types of errors
-            const nonRequiredErrors = newRowErrors[key as string].filter(
-              (e) => e.type !== ErrorType.Required
-            );
+          const isRequired = field.validations?.some((v) => v.rule === 'required');
+          const valueIsEmpty =
+            currentValue === undefined ||
+            currentValue === null ||
+            currentValue === '' ||
+            (Array.isArray(currentValue) && currentValue.length === 0) ||
+            (typeof currentValue === 'object' && currentValue !== null && Object.keys(currentValue).length === 0);
 
+          if (isRequired && !valueIsEmpty && newRowErrors[String(key)]) {
+            const nonRequiredErrors = newRowErrors[String(key)].filter((e) => e.type !== ErrorType.Required);
             if (nonRequiredErrors.length === 0) {
-              // If no other errors, delete the field's errors entirely
-              delete newRowErrors[key as string];
-            } else {
-              // Otherwise keep non-required errors
-              newRowErrors[key as string] = nonRequiredErrors;
+              if (newRowErrors[String(key)]) {
+                rowChanged = true;
+                delete newRowErrors[String(key)];
+              }
+            } else if (nonRequiredErrors.length !== newRowErrors[String(key)].length) {
+              rowChanged = true;
+              newRowErrors[String(key)] = nonRequiredErrors;
             }
           }
+
+          const errors = validateFieldFromHook(
+            currentValue,
+            field as unknown as Field<T>
+          ).filter((e) => e.type !== ErrorType.Required || valueIsEmpty);
+
+          if (errors.length > 0) {
+            const existing = newRowErrors[String(key)] || [];
+            const sameLength = existing.length === errors.length;
+            const sameContent = sameLength && existing.every((err, idx) => err.message === errors[idx].message && err.type === errors[idx].type);
+            if (!sameContent) {
+              rowChanged = true;
+              newRowErrors[String(key)] = errors;
+            }
+          } else if (newRowErrors[String(key)]) {
+            rowChanged = true;
+            delete newRowErrors[String(key)];
+          }
+
+          let resultMap = prev;
+          if (rowChanged) {
+            resultMap = new Map(prev);
+            if (Object.keys(newRowErrors).length > 0) {
+              resultMap.set(rowIndex, newRowErrors);
+            } else {
+              resultMap.delete(rowIndex);
+            }
+          }
+
+          const fieldsToCheck: string[] = [];
+          if (uniquenessFieldKeys.has(String(key))) fieldsToCheck.push(String(key));
+          if (key === ('upc' as T) || key === ('barcode' as T) || key === ('supplier' as T)) {
+            if (uniquenessFieldKeys.has('item_number')) fieldsToCheck.push('item_number');
+          }
+
+          if (fieldsToCheck.length > 0) {
+            scheduleUniqueValidation(fieldsToCheck);
+          }
+
+            return rowChanged ? resultMap : prev;
+          });
+      });
+
+      setTimeout(() => {
+        const rowId = rowData.__index;
+
+        if (key === 'company' && processedValue) {
+          const nextData = [...dataRef.current];
+          const idx = nextData.findIndex((item) => item.__index === rowId);
+          if (idx >= 0) {
+            nextData[idx] = {
+              ...nextData[idx],
+              line: undefined,
+              subline: undefined,
+            };
+            dataRef.current = nextData;
+            startTransition(() => {
+              setData(() => nextData);
+            });
+          }
         }
 
-        // Now run full validation for the field (except for required which we already handled)
-        const errors = validateFieldFromHook(
-          processedValue,
-          field as unknown as Field<T>
-        ).filter((e) => e.type !== ErrorType.Required || isEmpty);
-
-        // Update with new validation results
-        if (errors.length > 0) {
-          newRowErrors[key as string] = errors;
-        } else {
-          // Clear any existing errors for this field
-          delete newRowErrors[key as string];
+        if (key === 'line' && processedValue) {
+          const nextData = [...dataRef.current];
+          const idx = nextData.findIndex((item) => item.__index === rowId);
+          if (idx >= 0) {
+            nextData[idx] = {
+              ...nextData[idx],
+              subline: undefined,
+            };
+            dataRef.current = nextData;
+            startTransition(() => {
+              setData(() => nextData);
+            });
+          }
         }
-
-        // Update the map
-        if (Object.keys(newRowErrors).length > 0) {
-          newMap.set(rowIndex, newRowErrors);
-        } else {
-          newMap.delete(rowIndex);
-        }
-
-        // If uniqueness applies, validate affected columns
-        const fieldsToCheck: string[] = [];
-        if (uniquenessFieldKeys.has(String(key))) fieldsToCheck.push(String(key));
-        if (key === ('upc' as T) || key === ('barcode' as T) || key === ('supplier' as T)) {
-          if (uniquenessFieldKeys.has('item_number')) fieldsToCheck.push('item_number');
-        }
-
-        if (fieldsToCheck.length > 0) {
-          const dataForCalc = (() => {
-            const copy = [...data];
-            if (rowIndex >= 0 && rowIndex < copy.length) {
-              copy[rowIndex] = { ...(copy[rowIndex] || {}), [key]: processedValue } as RowData<T>;
-            }
-            return copy;
-          })();
-          newMap = mergeUniqueErrorsForFields(newMap, dataForCalc, fieldsToCheck);
-        }
-
-        return newMap;
-      });
-
-      // Handle simple secondary effects here
-      setTimeout(() => {
-        // Use __index to find the actual row in the full data array
-        const rowId = rowData.__index;
-
-        // Handle company change - clear line/subline
-        if (key === "company" && processedValue) {
-          // Clear any existing line/subline values
-          setData((prevData) => {
-            const newData = [...prevData];
-            const idx = newData.findIndex((item) => item.__index === rowId);
-            if (idx >= 0) {
-              newData[idx] = {
-                ...newData[idx],
-                line: undefined,
-                subline: undefined,
-              };
-            }
-            return newData;
-          });
-        }
-
-        // Handle line change - clear subline
-        if (key === "line" && processedValue) {
-          // Clear any existing subline value
-          setData((prevData) => {
-            const newData = [...prevData];
-            const idx = newData.findIndex((item) => item.__index === rowId);
-            if (idx >= 0) {
-              newData[idx] = {
-                ...newData[idx],
-                subline: undefined,
-              };
-            }
-            return newData;
-          });
-        }
-      }, 5); // Reduced delay for faster secondary effects
+      }, 5);
     },
-    [data, fields, validateFieldFromHook, setData, setValidationErrors, mergeUniqueErrorsForFields, uniquenessFieldKeys]
+    [fields, scheduleFieldValidation, scheduleUniqueValidation, setData, setValidationErrors, uniquenessFieldKeys, validateFieldFromHook]
   );
 
-  // Improved revalidateRows function
   const revalidateRows = useCallback(
     async (
       rowIndexes: number[],
       updatedFields?: { [rowIndex: number]: string[] }
     ) => {
-      // Process all specified rows using a single state update to avoid race conditions
+      const uniqueFieldsToCheck = new Set<string>();
+      const fieldsMarked: Array<[number, string]> = [];
+
       setValidationErrors((prev) => {
         let newErrors = new Map(prev);
+        const currentData = dataRef.current;
 
-        // Track which uniqueness fields need to be revalidated across the dataset
-        const uniqueFieldsToCheck = new Set<string>();
-
-        // Process each row
         for (const rowIndex of rowIndexes) {
-          if (rowIndex < 0 || rowIndex >= data.length) continue;
-
-          const row = data[rowIndex];
+          if (rowIndex < 0 || rowIndex >= currentData.length) continue;
+          const row = currentData[rowIndex];
           if (!row) continue;
 
-          // If we have specific fields to update for this row
           const fieldsToValidate = updatedFields?.[rowIndex] || [];
 
           if (fieldsToValidate.length > 0) {
-            // Get existing errors for this row
             const existingRowErrors = { ...(newErrors.get(rowIndex) || {}) };
 
-            // Validate each specified field
             for (const fieldKey of fieldsToValidate) {
               const field = fields.find((f) => String(f.key) === fieldKey);
               if (!field) continue;
 
-              const value = row[fieldKey as keyof typeof row];
+              updateValidatingCell(rowIndex, fieldKey, true);
+              fieldsMarked.push([rowIndex, fieldKey]);
 
-              // Run validation for this field
+              const value = row[fieldKey as keyof typeof row];
               const errors = validateFieldFromHook(value, field as unknown as Field<T>);
 
-              // Update errors for this field
               if (errors.length > 0) {
                 existingRowErrors[fieldKey] = errors;
               } else {
                 delete existingRowErrors[fieldKey];
               }
 
-              // If field is uniqueness-constrained, mark for uniqueness pass
               if (uniquenessFieldKeys.has(fieldKey)) {
                 uniqueFieldsToCheck.add(fieldKey);
               }
             }
 
-            // Update the row's errors
             if (Object.keys(existingRowErrors).length > 0) {
               newErrors.set(rowIndex, existingRowErrors);
             } else {
               newErrors.delete(rowIndex);
             }
           } else {
-            // No specific fields provided - validate the entire row
             const rowErrors: Record<string, ValidationError[]> = {};
 
-            // Validate all fields in the row
             for (const field of fields) {
               const fieldKey = String(field.key);
               const value = row[fieldKey as keyof typeof row];
-
-              // Run validation for this field
               const errors = validateFieldFromHook(value, field as unknown as Field<T>);
 
-              // Update errors for this field
               if (errors.length > 0) {
                 rowErrors[fieldKey] = errors;
               }
 
-              // If field is uniqueness-constrained and we validated it, include for uniqueness pass
               if (uniquenessFieldKeys.has(fieldKey)) {
                 uniqueFieldsToCheck.add(fieldKey);
               }
             }
 
-            // Update the row's errors
             if (Object.keys(rowErrors).length > 0) {
               newErrors.set(rowIndex, rowErrors);
             } else {
@@ -462,31 +544,40 @@ export const useRowOperations = <T extends string>(
           }
         }
 
-        // Run per-field uniqueness checks and merge results
-        if (uniqueFieldsToCheck.size > 0) {
-          newErrors = mergeUniqueErrorsForFields(newErrors, data, Array.from(uniqueFieldsToCheck));
-        }
-
         return newErrors;
       });
+
+      fieldsMarked.forEach(([rowIndex, fieldKey]) => {
+        updateValidatingCell(rowIndex, fieldKey, false);
+      });
+
+      if (uniqueFieldsToCheck.size > 0) {
+        scheduleUniqueValidation(Array.from(uniqueFieldsToCheck));
+      }
     },
-    [data, fields, validateFieldFromHook, mergeUniqueErrorsForFields, uniquenessFieldKeys]
+    [
+      fields,
+      scheduleUniqueValidation,
+      setValidationErrors,
+      uniquenessFieldKeys,
+      validateFieldFromHook,
+      updateValidatingCell
+    ]
   );
 
-  // Copy a cell value to all cells below it in the same column
   const copyDown = useCallback(
     (rowIndex: number, key: T) => {
-      // Get the source value to copy
-      const sourceValue = data[rowIndex][key];
+      const currentData = dataRef.current;
+      const sourceRow = currentData[rowIndex];
+      if (!sourceRow) return;
 
-      // Update all rows below with the same value using the existing updateRow function
-      // This ensures all validation logic runs consistently
-      for (let i = rowIndex + 1; i < data.length; i++) {
-        // Just use updateRow which will handle validation with proper timing
+      const sourceValue = sourceRow[key];
+
+      for (let i = rowIndex + 1; i < currentData.length; i++) {
         updateRow(i, key, sourceValue);
       }
     },
-    [data, updateRow]
+    [updateRow]
   );
 
   return {
@@ -495,4 +586,4 @@ export const useRowOperations = <T extends string>(
     revalidateRows,
     copyDown
   };
-}; 
+};
diff --git a/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useValidationState.tsx b/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useValidationState.tsx
index b3dd9ba..6ee15cf 100644
--- a/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useValidationState.tsx
+++ b/inventory/src/components/product-import/steps/ValidationStepNew/hooks/useValidationState.tsx
@@ -1,4 +1,4 @@
-import { useState, useEffect, useCallback, useMemo, useRef } from "react";
+import { useState, useEffect, useCallback, useMemo, useRef, startTransition } from "react";
 import { useRsi } from "../../../hooks/useRsi";
 import { ErrorType } from "../../../types";
 import { RowSelectionState } from "@tanstack/react-table";
@@ -11,7 +11,7 @@ import { useTemplateManagement } from "./useTemplateManagement";
 import { useFilterManagement } from "./useFilterManagement";
 import { useUniqueItemNumbersValidation } from "./useUniqueItemNumbersValidation";
 import { useUpcValidation } from "./useUpcValidation";
-import { Props, RowData } from "./validationTypes";
+import { Props, RowData, isEmpty as isValueEmpty } from "./validationTypes";
 
 // Country normalization helper (common mappings) - function declaration for hoisting
 function normalizeCountryCode(input: string): string | null {
@@ -145,6 +145,7 @@ export const useValidationState = <T extends string>({
   // isValidatingRef unused; remove to satisfy TS
   // Track last seen item_number signature to drive targeted uniqueness checks
   const lastItemNumberSigRef = useRef<string | null>(null);
+  const pendingItemNumberValidationRef = useRef<{ cancel: () => void } | null>(null);
 
   // Use row operations hook
   const { validateRow, updateRow, revalidateRows, copyDown } = useRowOperations<T>(
@@ -152,7 +153,8 @@ export const useValidationState = <T extends string>({
     fields,
     setData,
     setValidationErrors,
-    validateFieldFromHook
+    validateFieldFromHook,
+    setValidatingCells
   );
 
   // Use UPC validation hook - MUST be initialized before template management
@@ -306,313 +308,325 @@ export const useValidationState = <T extends string>({
   // Initialize validation once, after initial UPC-based item number generation completes
   useEffect(() => {
     if (initialValidationDoneRef.current) return;
-    // Wait for initial UPC validation to finish to avoid double work and ensure
-    // item_number values are in place before uniqueness checks
     if (!upcValidation.initialValidationDone) return;
+    if (!data || data.length === 0) return;
 
-    const runCompleteValidation = async () => {
-      if (!data || data.length === 0) return;
+    const requiredFields = fields.filter((field) =>
+      field.validations?.some((v) => v.rule === "required")
+    );
+    const regexFields = fields.filter((field) =>
+      field.validations?.some((v) => v.rule === "regex")
+    );
 
-      console.log("Running complete validation...");
+    const validationErrorsTemp = new Map<number, Record<string, any[]>>();
+    const mutatedRows: Array<[number, RowData<T>]> = [];
+    const totalRows = data.length;
+    let currentIndex = 0;
+    let cancelled = false;
 
-      // Get required fields
-      const requiredFields = fields.filter((field) =>
-        field.validations?.some((v) => v.rule === "required")
-      );
-      console.log(`Found ${requiredFields.length} required fields`);
+    const cleanupCallbacks = new Set<() => void>();
 
-      // Get fields that have regex validation
-      const regexFields = fields.filter((field) =>
-        field.validations?.some((v) => v.rule === "regex")
-      );
-      console.log(`Found ${regexFields.length} fields with regex validation`);
+    const processRow = (rowIndex: number) => {
+      const row = data[rowIndex];
+      if (!row) return;
 
-      // Get fields that need uniqueness validation
-      const uniqueFields = fields.filter((field) =>
-        field.validations?.some((v) => v.rule === "unique")
-      );
-      console.log(
-        `Found ${uniqueFields.length} fields requiring uniqueness validation`
-      );
+      const rowErrors: Record<string, any[]> = {};
+      let hasErrors = false;
 
-      // Dynamic batch size based on dataset size
-      const BATCH_SIZE = data.length <= 50 ? data.length : 25; // Process all at once for small datasets
-      const totalRows = data.length;
+      const rowAsRecord = row as Record<string, any>;
+      let updatedRow: Record<string, any> | null = null;
 
-      // Initialize new data for any modifications
-      const newData = [...data];
-
-      // Create a temporary Map to collect all validation errors
-      const validationErrorsTemp = new Map<
-        number,
-        Record<string, any[]>
-      >();
-
-      // Variables for batching
-      let currentBatch = 0;
-      const totalBatches = Math.ceil(totalRows / BATCH_SIZE);
-
-      const processBatch = async () => {
-        // Calculate batch range
-        const startIdx = currentBatch * BATCH_SIZE;
-        const endIdx = Math.min(startIdx + BATCH_SIZE, totalRows);
-        console.log(
-          `Processing batch ${
-            currentBatch + 1
-          }/${totalBatches} (rows ${startIdx} to ${endIdx - 1})`
-        );
-
-        // Process rows in this batch
-        const batchPromises: Promise<void>[] = [];
-
-        for (let rowIndex = startIdx; rowIndex < endIdx; rowIndex++) {
-          batchPromises.push(
-            new Promise<void>((resolve) => {
-              const row = data[rowIndex];
-
-              // Skip if row is empty or undefined
-              if (!row) {
-                resolve();
-                return;
-              }
-
-              // Store field errors for this row
-              const fieldErrors: Record<string, any[]> = {};
-              let hasErrors = false;
-
-              // Check if price fields need formatting
-              const rowAsRecord = row as Record<string, any>;
-              let mSrpNeedsProcessing = false;
-              let costEachNeedsProcessing = false;
-
-              if (
-                rowAsRecord.msrp &&
-                typeof rowAsRecord.msrp === "string" &&
-                (rowAsRecord.msrp.includes("$") ||
-                  rowAsRecord.msrp.includes(","))
-              ) {
-                mSrpNeedsProcessing = true;
-              }
-
-              if (
-                rowAsRecord.cost_each &&
-                typeof rowAsRecord.cost_each === "string" &&
-                (rowAsRecord.cost_each.includes("$") ||
-                  rowAsRecord.cost_each.includes(","))
-              ) {
-                costEachNeedsProcessing = true;
-              }
-
-              // Process price fields if needed
-              if (mSrpNeedsProcessing || costEachNeedsProcessing) {
-                // Create a clean copy only if needed
-                const cleanedRow = { ...row } as Record<string, any>;
-
-                if (mSrpNeedsProcessing) {
-                  const msrpValue = rowAsRecord.msrp.replace(/[$,]/g, "");
-                  const numValue = parseFloat(msrpValue);
-                  cleanedRow.msrp = !isNaN(numValue)
-                    ? numValue.toFixed(2)
-                    : msrpValue;
-                }
-
-                if (costEachNeedsProcessing) {
-                  const costValue = rowAsRecord.cost_each.replace(/[$,]/g, "");
-                  const numValue = parseFloat(costValue);
-                  cleanedRow.cost_each = !isNaN(numValue)
-                    ? numValue.toFixed(2)
-                    : costValue;
-                }
-
-                newData[rowIndex] = cleanedRow as RowData<T>;
-              }
-
-              // Validate required fields
-              for (const field of requiredFields) {
-                const key = String(field.key);
-                const value = row[key as keyof typeof row];
-
-                // Skip non-required empty fields
-                if (
-                  value === undefined ||
-                  value === null ||
-                  value === "" ||
-                  (Array.isArray(value) && value.length === 0) ||
-                  (typeof value === "object" &&
-                    value !== null &&
-                    Object.keys(value).length === 0)
-                ) {
-                  // Add error for empty required fields
-                  fieldErrors[key] = [
-                    {
-                      message:
-                        field.validations?.find((v) => v.rule === "required")
-                          ?.errorMessage || "This field is required",
-                      level: "error",
-                      source: "row",
-                      type: "required",
-                    },
-                  ];
-                  hasErrors = true;
-                }
-              }
-
-              // Validate regex fields - even if they have data
-              for (const field of regexFields) {
-                const key = String(field.key);
-                const value = row[key as keyof typeof row];
-
-                // Skip empty values as they're handled by required validation
-                if (value === undefined || value === null || value === "") {
-                  continue;
-                }
-
-                // Find regex validation
-                const regexValidation = field.validations?.find(
-                  (v) => v.rule === "regex"
-                );
-                if (regexValidation) {
-                  try {
-                    // Check if value matches regex
-                    const regex = new RegExp(
-                      regexValidation.value,
-                      regexValidation.flags
-                    );
-                    if (!regex.test(String(value))) {
-                      // Add regex validation error
-                      fieldErrors[key] = [
-                        {
-                          message: regexValidation.errorMessage,
-                          level: regexValidation.level || "error",
-                          source: "row",
-                          type: "regex",
-                        },
-                      ];
-                      hasErrors = true;
-                    }
-                  } catch (error) {
-                    console.error("Invalid regex in validation:", error);
-                  }
-                }
-              }
-
-              // Update validation errors for this row
-              if (hasErrors) {
-                validationErrorsTemp.set(rowIndex, fieldErrors);
-              }
-
-              resolve();
-            })
-          );
+      const ensureUpdatedRow = () => {
+        if (!updatedRow) {
+          updatedRow = { ...rowAsRecord };
         }
-
-        // Wait for all row validations to complete
-        await Promise.all(batchPromises);
+        return updatedRow;
       };
 
-      const processAllBatches = async () => {
-        for (let batch = 0; batch < totalBatches; batch++) {
-          currentBatch = batch;
-          await processBatch();
+      if (typeof rowAsRecord.msrp === "string" && /[$,]/.test(rowAsRecord.msrp)) {
+        const msrpValue = rowAsRecord.msrp.replace(/[$,]/g, "");
+        const numValue = parseFloat(msrpValue);
+        ensureUpdatedRow().msrp = Number.isNaN(numValue) ? msrpValue : numValue.toFixed(2);
+      }
 
-          // Yield to UI thread more frequently for large datasets
-          if (batch % 2 === 1 || totalRows > 500) {
-            await new Promise((resolve) => setTimeout(resolve, totalRows > 1000 ? 10 : 5));
+      if (typeof rowAsRecord.cost_each === "string" && /[$,]/.test(rowAsRecord.cost_each)) {
+        const costValue = rowAsRecord.cost_each.replace(/[$,]/g, "");
+        const numValue = parseFloat(costValue);
+        ensureUpdatedRow().cost_each = Number.isNaN(numValue) ? costValue : numValue.toFixed(2);
+      }
+
+      for (const field of requiredFields) {
+        const key = String(field.key);
+        const value = rowAsRecord[key];
+
+        if (isValueEmpty(value)) {
+          rowErrors[key] = [
+            {
+              message:
+                field.validations?.find((v) => v.rule === "required")?.errorMessage ||
+                "This field is required",
+              level: "error",
+              source: "row",
+              type: "required",
+            },
+          ];
+          hasErrors = true;
+        }
+      }
+
+      for (const field of regexFields) {
+        const key = String(field.key);
+        const value = rowAsRecord[key];
+        if (value === undefined || value === null || value === "") continue;
+
+        const regexValidation = field.validations?.find((v) => v.rule === "regex");
+        if (!regexValidation) continue;
+
+        try {
+          const regex = new RegExp(regexValidation.value, regexValidation.flags);
+          if (!regex.test(String(value))) {
+            rowErrors[key] = [
+              {
+                message: regexValidation.errorMessage,
+                level: regexValidation.level || "error",
+                source: "row",
+                type: "regex",
+              },
+            ];
+            hasErrors = true;
           }
+        } catch (error) {
+          console.error("Invalid regex in validation:", error);
         }
+      }
 
-        // All batches complete
-        console.log("All initial validation batches complete");
+      if (updatedRow) {
+        mutatedRows.push([rowIndex, updatedRow as RowData<T>]);
+      }
 
-        // Apply collected validation errors all at once
-        setValidationErrors(validationErrorsTemp);
-
-        // Apply any data changes (like price formatting)
-        if (JSON.stringify(data) !== JSON.stringify(newData)) {
-          setData(newData);
-        }
-
-        // Run uniqueness validation after the basic validation
-        validateUniqueItemNumbers();
-
-        // Mark that initial validation is done
-        initialValidationDoneRef.current = true;
-
-        console.log("Initial validation complete");
-      };
-
-      // Start the validation process
-      processAllBatches();
+      if (hasErrors) {
+        validationErrorsTemp.set(rowIndex, rowErrors);
+      }
     };
 
-    // Run the complete validation
-    runCompleteValidation();
+    const finalize = () => {
+      if (cancelled) return;
+
+      startTransition(() => {
+        setValidationErrors(new Map(validationErrorsTemp));
+      });
+
+      if (mutatedRows.length > 0) {
+        setData((prev) => {
+          if (cancelled) return prev;
+          let applied = false;
+          const next = [...prev];
+
+          mutatedRows.forEach(([index, updatedRow]) => {
+            if (index < 0 || index >= prev.length) return;
+            if (prev[index] !== data[index]) return;
+            next[index] = updatedRow;
+            applied = true;
+          });
+
+          return applied ? next : prev;
+        });
+      }
+
+      validateUniqueItemNumbers();
+      initialValidationDoneRef.current = true;
+    };
+
+    const runChunk = (deadline?: IdleDeadline) => {
+      if (cancelled) return;
+
+      let iterations = 0;
+      const maxIterationsPerChunk = 20;
+
+      while (currentIndex < totalRows) {
+        if (deadline) {
+          if (deadline.timeRemaining() <= 0 && iterations > 0) break;
+        } else if (iterations >= maxIterationsPerChunk) {
+          break;
+        }
+
+        processRow(currentIndex);
+        currentIndex += 1;
+        iterations += 1;
+      }
+
+      if (currentIndex >= totalRows) {
+        finalize();
+        return;
+      }
+
+      scheduleNext();
+    };
+
+    const scheduleNext = () => {
+      if (cancelled) return;
+
+      if (typeof window !== 'undefined') {
+        const win = window as Window & typeof globalThis & {
+          requestIdleCallback?: (callback: IdleRequestCallback, options?: IdleRequestOptions) => number;
+          cancelIdleCallback?: (handle: number) => void;
+        };
+
+        if (win.requestIdleCallback) {
+          let cancel: () => void = () => {};
+          const handle = win.requestIdleCallback((deadline) => {
+            cleanupCallbacks.delete(cancel);
+            runChunk(deadline);
+          }, { timeout: 250 });
+          cancel = () => win.cancelIdleCallback?.(handle);
+          cleanupCallbacks.add(cancel);
+          return;
+        }
+
+        let cancel: () => void = () => {};
+        const timeoutId = window.setTimeout(() => {
+          cleanupCallbacks.delete(cancel);
+          runChunk();
+        }, 16);
+        cancel = () => window.clearTimeout(timeoutId);
+        cleanupCallbacks.add(cancel);
+        return;
+      }
+
+      setTimeout(() => runChunk(), 0);
+    };
+
+    scheduleNext();
+
+    return () => {
+      cancelled = true;
+      cleanupCallbacks.forEach((cancel) => cancel());
+      cleanupCallbacks.clear();
+    };
   }, [data, fields, setData, setValidationErrors, validateUniqueItemNumbers, upcValidation.initialValidationDone]);
 
   // Targeted uniqueness revalidation: run only when item_number values change
   useEffect(() => {
     if (!data || data.length === 0) return;
 
-    // Build a simple signature of the item_number column
-    const sig = data.map((r) => String((r as Record<string, any>).item_number ?? '')).join('|');
+    const sig = data
+      .map((r) => String((r as Record<string, any>).item_number ?? ''))
+      .join('|');
     if (lastItemNumberSigRef.current === sig) return;
     lastItemNumberSigRef.current = sig;
 
-    // Compute unique errors for item_number only and merge
-    const uniqueMap = validateUniqueField(data, 'item_number');
-    const rowsWithUnique = new Set<number>();
-    uniqueMap.forEach((_, idx) => rowsWithUnique.add(idx));
+    pendingItemNumberValidationRef.current?.cancel();
 
-    setValidationErrors((prev) => {
-      const newMap = new Map(prev);
+    let cancelled = false;
+    const currentData = data;
 
-      // Apply unique errors
-      uniqueMap.forEach((errorsForRow, rowIdx) => {
-        const existing = { ...(newMap.get(rowIdx) || {}) } as Record<string, any[]>;
-        const info = (errorsForRow as any)['item_number'];
-        const currentValue = (data[rowIdx] as any)?.['item_number'];
-        // Only apply uniqueness error when the value is non-empty
-        if (info && currentValue !== undefined && currentValue !== null && String(currentValue) !== '') {
-          existing['item_number'] = [
-            {
-              message: info.message,
-              level: info.level,
-              source: info.source,
-              type: info.type,
-            },
-          ];
-        }
-        // If value is now present, make sure to clear any lingering Required error
-        if (currentValue !== undefined && currentValue !== null && String(currentValue) !== '' && existing['item_number']) {
-          existing['item_number'] = (existing['item_number'] as any[]).filter((e) => e.type !== ErrorType.Required);
-          if ((existing['item_number'] as any[]).length === 0) delete existing['item_number'];
-        }
-        if (Object.keys(existing).length > 0) newMap.set(rowIdx, existing);
-        else newMap.delete(rowIdx);
+    const runValidation = () => {
+      if (cancelled) return;
+
+      const uniqueMap = validateUniqueField(currentData, 'item_number');
+      const rowsWithUnique = new Set<number>();
+      uniqueMap.forEach((_, idx) => rowsWithUnique.add(idx));
+
+      startTransition(() => {
+        setValidationErrors((prev) => {
+          const newMap = new Map(prev);
+
+          uniqueMap.forEach((errorsForRow, rowIdx) => {
+          const existing = { ...(newMap.get(rowIdx) || {}) } as Record<string, any[]>;
+          const info = (errorsForRow as any)['item_number'];
+          const currentValue = (currentData[rowIdx] as any)?.['item_number'];
+
+          if (info && currentValue !== undefined && currentValue !== null && String(currentValue) !== '') {
+            existing['item_number'] = [
+              {
+                message: info.message,
+                level: info.level,
+                source: info.source,
+                type: info.type,
+              },
+            ];
+          }
+
+          if (currentValue !== undefined && currentValue !== null && String(currentValue) !== '' && existing['item_number']) {
+            existing['item_number'] = (existing['item_number'] as any[]).filter((e) => e.type !== ErrorType.Required);
+            if ((existing['item_number'] as any[]).length === 0) delete existing['item_number'];
+          }
+
+          if (Object.keys(existing).length > 0) newMap.set(rowIdx, existing);
+          else newMap.delete(rowIdx);
+        });
+
+        newMap.forEach((rowErrs, rowIdx) => {
+          const currentValue = (currentData[rowIdx] as any)?.['item_number'];
+          const shouldRemoveUnique =
+            !rowsWithUnique.has(rowIdx) ||
+            currentValue === undefined ||
+            currentValue === null ||
+            String(currentValue) === '';
+
+          if (shouldRemoveUnique && (rowErrs as any)['item_number']) {
+            const filtered = (rowErrs as any)['item_number'].filter((e: any) => e.type !== ErrorType.Unique);
+            if (filtered.length > 0) (rowErrs as any)['item_number'] = filtered;
+            else delete (rowErrs as any)['item_number'];
+          }
+
+          if (currentValue !== undefined && currentValue !== null && String(currentValue) !== '' && (rowErrs as any)['item_number']) {
+            const nonRequired = (rowErrs as any)['item_number'].filter((e: any) => e.type !== ErrorType.Required);
+            if (nonRequired.length > 0) (rowErrs as any)['item_number'] = nonRequired;
+            else delete (rowErrs as any)['item_number'];
+          }
+
+          if (Object.keys(rowErrs).length > 0) newMap.set(rowIdx, rowErrs);
+          else newMap.delete(rowIdx);
+        });
+
+          return newMap;
+        });
       });
+    };
 
-      // Remove stale unique errors for rows no longer duplicated
-      newMap.forEach((rowErrs, rowIdx) => {
-        const currentValue = (data[rowIdx] as any)?.['item_number'];
-        const shouldRemoveUnique = !rowsWithUnique.has(rowIdx) || currentValue === undefined || currentValue === null || String(currentValue) === '';
-        if (shouldRemoveUnique && (rowErrs as any)['item_number']) {
-          const filtered = (rowErrs as any)['item_number'].filter((e: any) => e.type !== ErrorType.Unique);
-          if (filtered.length > 0) (rowErrs as any)['item_number'] = filtered;
-          else delete (rowErrs as any)['item_number'];
-        }
-        // If value now present, also clear any lingering Required error for this field
-        if (currentValue !== undefined && currentValue !== null && String(currentValue) !== '' && (rowErrs as any)['item_number']) {
-          const nonRequired = (rowErrs as any)['item_number'].filter((e: any) => e.type !== ErrorType.Required);
-          if (nonRequired.length > 0) (rowErrs as any)['item_number'] = nonRequired;
-          else delete (rowErrs as any)['item_number'];
-        }
+    const schedule = () => {
+      if (typeof window === 'undefined') {
+        runValidation();
+        return;
+      }
 
-        if (Object.keys(rowErrs).length > 0) newMap.set(rowIdx, rowErrs);
-        else newMap.delete(rowIdx);
-      });
+      const win = window as Window & typeof globalThis & {
+        requestIdleCallback?: (callback: IdleRequestCallback, options?: IdleRequestOptions) => number;
+        cancelIdleCallback?: (handle: number) => void;
+      };
 
-      return newMap;
-    });
+      if (win.requestIdleCallback) {
+        const handle = win.requestIdleCallback(() => {
+          pendingItemNumberValidationRef.current = null;
+          if (cancelled) return;
+          runValidation();
+        }, { timeout: 250 });
+
+        pendingItemNumberValidationRef.current = {
+          cancel: () => win.cancelIdleCallback?.(handle),
+        };
+        return;
+      }
+
+      const timeoutId = window.setTimeout(() => {
+        pendingItemNumberValidationRef.current = null;
+        if (cancelled) return;
+        runValidation();
+      }, 16);
+
+      pendingItemNumberValidationRef.current = {
+        cancel: () => window.clearTimeout(timeoutId),
+      };
+    };
+
+    schedule();
+
+    return () => {
+      cancelled = true;
+      pendingItemNumberValidationRef.current?.cancel();
+      pendingItemNumberValidationRef.current = null;
+    };
   }, [data, validateUniqueField, setValidationErrors]);
 
   // Update fields with latest options