diff --git a/app/customize/components/AdvancedSettingsPanel.massive_scaling.test.tsx b/app/customize/components/AdvancedSettingsPanel.massive_scaling.test.tsx
new file mode 100644
index 000000000..b881ad71b
--- /dev/null
+++ b/app/customize/components/AdvancedSettingsPanel.massive_scaling.test.tsx
@@ -0,0 +1,138 @@
+import { render, screen, fireEvent } from '@testing-library/react';
+import { describe, expect, it, vi, beforeEach } from 'vitest';
+
+import { AdvancedSettingsPanel } from './AdvancedSettingsPanel';
+import type { DeltaFormat, Language, Timezone, ViewMode } from '../types';
+
+const createProps = () => ({
+  hideTitle: false,
+  hideBackground: false,
+  hideStats: false,
+  viewMode: 'default' as ViewMode,
+  deltaFormat: 'percent' as DeltaFormat,
+  badgeWidth: 1200,
+  badgeHeight: 800,
+  grace: 7,
+  language: 'en' as Language,
+  timezone: 'UTC' as Timezone,
+
+  onHideTitleChange: vi.fn(),
+  onHideBackgroundChange: vi.fn(),
+  onHideStatsChange: vi.fn(),
+  onViewModeChange: vi.fn(),
+  onDeltaFormatChange: vi.fn(),
+  onBadgeWidthChange: vi.fn(),
+  onBadgeHeightChange: vi.fn(),
+  onGraceChange: vi.fn(),
+  onLanguageChange: vi.fn(),
+  onTimezoneChange: vi.fn(),
+});
+
+describe('AdvancedSettingsPanel - Massive Data Sets & Extreme High Bounds Scaling', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('renders successfully with maximum supported dimension values', () => {
+    render(<AdvancedSettingsPanel {...createProps()} />);
+
+    expect(screen.getByLabelText(/width/i)).toHaveValue(1200);
+    expect(screen.getByLabelText(/height/i)).toHaveValue(800);
+    expect(screen.getByLabelText(/grace days/i)).toBeInTheDocument();
+  });
+
+  it('handles repeated width updates across large value ranges', () => {
+    const props = createProps();
+
+    render(<AdvancedSettingsPanel {...props} />);
+
+    const widthInput = screen.getByLabelText(/width/i);
+
+    for (let width = 100; width <= 1200; width += 100) {
+      fireEvent.change(widthInput, {
+        target: { value: String(width) },
+      });
+    }
+
+    expect(props.onBadgeWidthChange).toHaveBeenCalled();
+
+    const lastWidth = props.onBadgeWidthChange.mock.lastCall?.[0];
+
+    expect(lastWidth).toBeGreaterThanOrEqual(100);
+    expect(lastWidth).toBeLessThanOrEqual(1200);
+  });
+
+  it('handles repeated height updates across extreme bounds', () => {
+    const props = createProps();
+
+    render(<AdvancedSettingsPanel {...props} />);
+
+    const heightInput = screen.getByLabelText(/height/i);
+
+    for (let height = 80; height <= 800; height += 80) {
+      fireEvent.change(heightInput, {
+        target: { value: String(height) },
+      });
+    }
+
+    expect(props.onBadgeHeightChange).toHaveBeenCalled();
+
+    const lastHeight = props.onBadgeHeightChange.mock.lastCall?.[0];
+
+    expect(lastHeight).toBeGreaterThanOrEqual(80);
+    expect(lastHeight).toBeLessThanOrEqual(800);
+  });
+
+  it('processes rapid grace slider updates across the full supported range', () => {
+    const props = createProps();
+
+    render(<AdvancedSettingsPanel {...props} />);
+
+    const slider = screen.getByLabelText(/grace days/i);
+
+    for (let grace = 0; grace <= 7; grace++) {
+      fireEvent.change(slider, {
+        target: { value: String(grace) },
+      });
+    }
+
+    expect(props.onGraceChange).toHaveBeenCalled();
+
+    const lastGrace = props.onGraceChange.mock.lastCall?.[0];
+
+    expect(lastGrace).toBeGreaterThanOrEqual(0);
+    expect(lastGrace).toBeLessThanOrEqual(7);
+  });
+
+  it('remains stable during high-volume mixed control interactions', () => {
+    const props = createProps();
+
+    render(<AdvancedSettingsPanel {...props} />);
+
+    const widthInput = screen.getByLabelText(/width/i);
+    const heightInput = screen.getByLabelText(/height/i);
+    const slider = screen.getByLabelText(/grace days/i);
+
+    for (let i = 0; i < 50; i++) {
+      fireEvent.change(widthInput, {
+        target: { value: String(800 + (i % 400)) },
+      });
+
+      fireEvent.change(heightInput, {
+        target: { value: String(600 + (i % 200)) },
+      });
+
+      fireEvent.change(slider, {
+        target: { value: String(i % 8) },
+      });
+    }
+
+    expect(props.onBadgeWidthChange).toHaveBeenCalled();
+    expect(props.onBadgeHeightChange).toHaveBeenCalled();
+    expect(props.onGraceChange).toHaveBeenCalled();
+
+    expect(screen.getByLabelText(/width/i)).toBeInTheDocument();
+    expect(screen.getByLabelText(/height/i)).toBeInTheDocument();
+    expect(screen.getByLabelText(/grace days/i)).toBeInTheDocument();
+  });
+});