diff --git a/lib/features/workspace/result_grid_view.dart b/lib/features/workspace/result_grid_view.dart
index 71e5172..22d62cc 100644
--- a/lib/features/workspace/result_grid_view.dart
+++ b/lib/features/workspace/result_grid_view.dart
@@ -696,6 +696,19 @@ class _VirtualResultGridState extends material.State<VirtualResultGrid> {
   bool _userHasResized = false;
   double _scrollOffset = 0;
 
+  /// Cache for [distributeResultGridSpareWidth] (#982): sampling every
+  /// column's header/content width is O(columns x sampled rows) and only
+  /// needs to rerun when [_columnWidths] itself was recomputed (a new list,
+  /// so `identical` catches it) or the viewport width changed, not on every
+  /// `LayoutBuilder` layout pass.
+  List<double> _distributedWidths = const [];
+  List<double>? _distributedForColumnWidths;
+  double? _distributedForAvailableWidth;
+
+  /// Counts calls to [distributeResultGridSpareWidth], i.e. cache misses.
+  @material.visibleForTesting
+  int columnWidthDistributionCount = 0;
+
   int? _sortColumnIndex;
   ResultGridSortOrder? _sortOrder;
   int _sortVersion = 0;
@@ -2098,14 +2111,23 @@ class _VirtualResultGridState extends material.State<VirtualResultGrid> {
               if (!_userHasResized &&
                   tableWidth < availableWidth &&
                   _columnWidths.isNotEmpty) {
-                displayWidths = distributeResultGridSpareWidth(
-                  columnWidths: _columnWidths,
-                  columns: widget.columns,
-                  rows: _baseRows,
-                  availableWidth: availableWidth,
-                  maxColumnWidth:
-                      context.scaled(ResultGridMetrics.maxColumnWidth),
-                );
+                if (identical(_distributedForColumnWidths, _columnWidths) &&
+                    _distributedForAvailableWidth == availableWidth) {
+                  displayWidths = _distributedWidths;
+                } else {
+                  displayWidths = distributeResultGridSpareWidth(
+                    columnWidths: _columnWidths,
+                    columns: widget.columns,
+                    rows: _baseRows,
+                    availableWidth: availableWidth,
+                    maxColumnWidth:
+                        context.scaled(ResultGridMetrics.maxColumnWidth),
+                  );
+                  _distributedWidths = displayWidths;
+                  _distributedForColumnWidths = _columnWidths;
+                  _distributedForAvailableWidth = availableWidth;
+                  columnWidthDistributionCount++;
+                }
                 final distributedWidth =
                     displayWidths.fold<double>(0.0, (sum, w) => sum + w);
                 tableWidth = math.max(distributedWidth, availableWidth);
diff --git a/test/features/workspace/result_grid_column_width_cache_test.dart b/test/features/workspace/result_grid_column_width_cache_test.dart
new file mode 100644
index 0000000..7fdd8fc
--- /dev/null
+++ b/test/features/workspace/result_grid_column_width_cache_test.dart
@@ -0,0 +1,82 @@
+import 'package:flutter/material.dart' as material;
+import 'package:flutter_test/flutter_test.dart';
+import 'package:querya_desktop/features/workspace/result_grid_view.dart';
+
+import '../../support/querya_theme_test_shell.dart';
+
+material.Widget _testShell({required material.Widget child}) {
+  return queryaThemeTestShell(
+    child: material.Scaffold(
+      body: child,
+    ),
+  );
+}
+
+void main() {
+  group('VirtualResultGrid column-width distribution cache (#982)', () {
+    testWidgets(
+        'an unrelated setState (same width, same columns/rows) does not resample column widths again',
+        (tester) async {
+      await tester.pumpWidget(
+        _testShell(
+          child: const material.SizedBox(
+            width: 800,
+            height: 400,
+            child: VirtualResultGrid(
+              columns: ['id', 'name', 'role'],
+              rows: [
+                ['1', 'Alice', 'Admin'],
+                ['2', 'Bob', 'User'],
+              ],
+            ),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      final dynamic state = tester.state(find.byType(VirtualResultGrid));
+      final firstCount = state.columnWidthDistributionCount as int;
+      expect(firstCount, greaterThanOrEqualTo(1));
+
+      // Force a rebuild of the grid's own State without touching its widget
+      // (rows/columns/width all unchanged) — the same shape of rebuild a
+      // selection change or any other internal setState would cause. The
+      // O(columns x rows) sampling must not rerun for it.
+      state.setState(() {});
+      await tester.pumpAndSettle();
+
+      expect(state.columnWidthDistributionCount, firstCount);
+    });
+
+    testWidgets('resizing the viewport does resample column widths',
+        (tester) async {
+      final key = material.GlobalKey();
+
+      material.Widget build(double width) => _testShell(
+            child: material.SizedBox(
+              key: key,
+              width: width,
+              height: 400,
+              child: const VirtualResultGrid(
+                columns: ['id', 'name', 'role'],
+                rows: [
+                  ['1', 'Alice', 'Admin'],
+                  ['2', 'Bob', 'User'],
+                ],
+              ),
+            ),
+          );
+
+      await tester.pumpWidget(build(800));
+      await tester.pumpAndSettle();
+
+      final dynamic state = tester.state(find.byType(VirtualResultGrid));
+      final firstCount = state.columnWidthDistributionCount as int;
+
+      await tester.pumpWidget(build(500));
+      await tester.pumpAndSettle();
+
+      expect(state.columnWidthDistributionCount, greaterThan(firstCount));
+    });
+  });
+}