diff --git a/content.js b/content.js
index 4816eb2..4a5b4b3 100644
--- a/content.js
+++ b/content.js
@@ -2385,13 +2385,22 @@ class YTMBlockController {
     console.log('[YTM Block Debug] normalized song:', normalizedInput);
     console.log('[YTM Block Debug] blockedSongs array:', this.blockedSongs);
 
-    for (const blocked of this.blockedSongs) {
-      const normalizedBlocked = this.normalizeSongTitle(blocked);
+    // Cache normalized versions of blocked songs to avoid redundant normalization per iteration
+    if (!this._normalizedBlockedSongsCache || this._normalizedBlockedSongsSource !== this.blockedSongs) {
+      this._normalizedBlockedSongsSource = this.blockedSongs;
+      this._normalizedBlockedSongsCache = this.blockedSongs.map((blocked) => ({
+        raw: blocked,
+        normalized: this.normalizeSongTitle(blocked)
+      }));
+    }
+
+    for (const item of this._normalizedBlockedSongsCache) {
+      const normalizedBlocked = item.normalized;
       if (normalizedInput === normalizedBlocked || 
           normalizedInput.includes(normalizedBlocked) || 
           normalizedBlocked.includes(normalizedInput)) {
-        console.log('[YTM Block Debug] shouldBlockSong result:', blocked);
-        return blocked;
+        console.log('[YTM Block Debug] shouldBlockSong result:', item.raw);
+        return item.raw;
       }
     }
     console.log('[YTM Block Debug] shouldBlockSong result: null');
diff --git a/tests/shouldBlockSong.test.js b/tests/shouldBlockSong.test.js
new file mode 100644
index 0000000..6b8cd20
--- /dev/null
+++ b/tests/shouldBlockSong.test.js
@@ -0,0 +1,59 @@
+const test = require('node:test');
+const assert = require('node:assert');
+const { performance } = require('node:perf_hooks');
+const { YTMBlockController } = require('../content.js');
+
+test('YTMBlockController - shouldBlockSong correctness', async (t) => {
+  const controller = new YTMBlockController();
+
+  await t.test('returns null when songTitle is empty or blockedSongs is empty', () => {
+    controller.blockedSongs = [];
+    assert.strictEqual(controller.shouldBlockSong('Some Song'), null);
+
+    controller.blockedSongs = ['Some Song'];
+    assert.strictEqual(controller.shouldBlockSong(''), null);
+    assert.strictEqual(controller.shouldBlockSong(null), null);
+  });
+
+  await t.test('matches exact, substring, or superstring blocked songs', () => {
+    controller.blockedSongs = ['Radioactive (Official Video)', 'Believer'];
+
+    // Exact match normalized
+    assert.strictEqual(controller.shouldBlockSong('Radioactive'), 'Radioactive (Official Video)');
+    assert.strictEqual(controller.shouldBlockSong('Believer'), 'Believer');
+
+    // Substring match
+    assert.strictEqual(controller.shouldBlockSong('Believer (Remix)'), 'Believer');
+
+    // Non-match
+    assert.strictEqual(controller.shouldBlockSong('Demons'), null);
+  });
+});
+
+test('YTMBlockController - shouldBlockSong performance benchmark', async (t) => {
+  const controller = new YTMBlockController();
+
+  await t.test('benchmark performance of song blocking evaluation', () => {
+    const blockedSongs = [];
+    for (let i = 0; i < 100; i++) {
+      blockedSongs.push(`Blocked Song Title Number ${i} (Official Audio) [Remastered 2023]`);
+    }
+    controller.blockedSongs = blockedSongs;
+
+    const testSong = 'Unblocked Song Title (Live at Wembley Stadium 2020) [Deluxe Edition]';
+
+    // Warmup JIT
+    for (let i = 0; i < 100; i++) {
+      controller.shouldBlockSong(testSong);
+    }
+
+    const iterations = 5000;
+    const start = performance.now();
+    for (let i = 0; i < iterations; i++) {
+      controller.shouldBlockSong(testSong);
+    }
+    const duration = performance.now() - start;
+
+    console.log(`[Benchmark] ${iterations} shouldBlockSong calls duration: ${duration.toFixed(2)}ms`);
+  });
+});