diff --git a/lib/svg/fonts.massive-scaling.test.ts b/lib/svg/fonts.massive-scaling.test.ts
new file mode 100644
index 000000000..cb879dfea
--- /dev/null
+++ b/lib/svg/fonts.massive-scaling.test.ts
@@ -0,0 +1,77 @@
+import { describe, expect, it } from 'vitest';
+
+import FONT_MAP, { resolveFont, isPredefinedFontKey } from './fonts';
+
+describe('fonts Massive Data Sets and Extreme High Bounds Scaling', () => {
+  it('resolves thousands of predefined font lookups without degradation', () => {
+    const start = performance.now();
+
+    const results = Array.from({ length: 10000 }, () => resolveFont('jetbrains'));
+
+    const duration = performance.now() - start;
+
+    expect(results).toHaveLength(10000);
+
+    results.forEach((font) => {
+      expect(font).toBe(FONT_MAP.jetbrains);
+    });
+
+    expect(duration).toBeLessThan(1000);
+  });
+
+  it('resolves thousands of unique custom font names correctly', () => {
+    const customFonts = Array.from({ length: 5000 }, (_, index) => `CustomFont${index}`);
+
+    const resolved = customFonts.map((font) => resolveFont(font));
+
+    expect(resolved).toHaveLength(5000);
+
+    expect(resolved[0]).toBe('"CustomFont0", sans-serif');
+    expect(resolved[4999]).toBe('"CustomFont4999", sans-serif');
+  });
+
+  it('handles massive predefined font key validation operations', () => {
+    const start = performance.now();
+
+    const checks = Array.from({ length: 15000 }, (_, index) =>
+      isPredefinedFontKey(index % 2 === 0 ? 'roboto' : 'jetbrains')
+    );
+
+    const duration = performance.now() - start;
+
+    expect(checks.every(Boolean)).toBe(true);
+
+    expect(duration).toBeLessThan(1000);
+  });
+
+  it('processes mixed valid and invalid font inputs at scale', () => {
+    const inputs = Array.from({ length: 10000 }, (_, index) => {
+      if (index % 4 === 0) return 'jetbrains';
+      if (index % 4 === 1) return 'Inter';
+      if (index % 4 === 2) return '';
+      return undefined;
+    });
+
+    const results = inputs.map((font) => resolveFont(font));
+
+    expect(results).toHaveLength(10000);
+
+    expect(results.filter((value) => value === null).length).toBeGreaterThan(0);
+
+    expect(results.filter((value) => value === FONT_MAP.jetbrains).length).toBeGreaterThan(0);
+
+    expect(results.filter((value) => value === '"Inter", sans-serif').length).toBeGreaterThan(0);
+  });
+
+  it('maintains consistent output during repeated high-volume execution cycles', () => {
+    for (let cycle = 0; cycle < 100; cycle++) {
+      expect(resolveFont('spacegrotesk')).toBe('"Space Grotesk", sans-serif');
+
+      expect(resolveFont('jetbrains')).toBe('"JetBrains Mono", monospace');
+
+      expect(isPredefinedFontKey('spacegrotesk')).toBe(true);
+
+      expect(isPredefinedFontKey('Inter')).toBe(false);
+    }
+  });
+});