diff --git a/.jules/bolt.md b/.jules/bolt.md
index d54cf10f..2c0d1c4f 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -61,3 +61,4 @@
 ## 2026-07-13 - Array.from mapping optimization
 **Learning:** Using `Array.from({ length: N }).map(...)` creates an intermediate array of `undefined` values which requires memory allocation and garbage collection, adding O(N) unnecessary overhead in frequently re-rendered UI components.
 **Action:** Use `Array.from({ length: N }, (_, index) => ...)` to map elements directly during array creation, avoiding intermediate allocations.
+## 2026-08-02 - O(1) Memory Array Validation\n**Learning:** Using `Array.every()` on large byte arrays in `scoreStorage.ts` allocates unnecessary intermediate callbacks (O(N) overhead) causing garbage collection spikes.\n**Action:** Replaced `.every()` with a standard `for` loop that avoids callback overhead and exits early upon encountering a non-number.\n
diff --git a/apps/desktop/src/features/score/scoreStorage.ts b/apps/desktop/src/features/score/scoreStorage.ts
index 492f1259..88a1706d 100644
--- a/apps/desktop/src/features/score/scoreStorage.ts
+++ b/apps/desktop/src/features/score/scoreStorage.ts
@@ -91,8 +91,19 @@ export async function readScorePdf(projectId: string, scoreId: string): Promise<
   if (response instanceof ArrayBuffer) {
     return new Uint8Array(response);
   }
-  if (Array.isArray(response) && response.every((byte) => typeof byte === "number")) {
-    return Uint8Array.from(response as number[]);
+  if (Array.isArray(response)) {
+    // Performance: Avoid .every() on large byte arrays as it creates O(N) intermediate callback allocations.
+    // Use a standard for loop with an early return to achieve O(1) memory and significantly faster execution.
+    let isNumberArray = true;
+    for (let i = 0; i < response.length; i++) {
+      if (typeof response[i] !== "number") {
+        isNumberArray = false;
+        break;
+      }
+    }
+    if (isNumberArray) {
+      return Uint8Array.from(response as number[]);
+    }
   }
 
   throw new Error(INVALID_RESPONSE_MESSAGE);