From 1e196270a0388cc204c1f64af05831220f8fe534 Mon Sep 17 00:00:00 2001
From: seonghobae <8172694+seonghobae@users.noreply.github.com>
Date: Fri, 17 Jul 2026 04:01:35 +0000
Subject: [PATCH] =?UTF-8?q?=E2=9A=A1=20Bolt:=20=EB=8C=80=EA=B7=9C=EB=AA=A8?=
 =?UTF-8?q?=20=EB=B0=B0=EC=97=B4=EC=97=90=EC=84=9C=20`Math.max`=20?=
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`apps/desktop/src/features/workspace/GrooveMap.tsx`에서 `renderedNotes.reduce`와 `Math.max`를 사용하는 부분을 표준 `for` 루프로 교체했습니다. 이 최적화는 큰 배열(예: 많은 전사 노트)을 처리할 때 반복마다 발생하는 클로저 할당과 함수 호출 오버헤드를 줄여 실행 속도를 높입니다.
---
 .jules/bolt.md                                    | 4 ++++
 apps/desktop/src/features/workspace/GrooveMap.tsx | 9 ++++++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/.jules/bolt.md b/.jules/bolt.md
index d54cf10f..c9e5b63e 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -61,3 +61,7 @@
 ## 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.
+
+## 2026-07-14 - O(N) iteration with reduced function overhead for finding maximum values
+**Learning:** Using `Array.prototype.reduce()` coupled with `Math.max()` to find the maximum value in a large array (like transcription notes) introduces significant function call overhead, allocating intermediate closures for each item.
+**Action:** Prefer standard `for` loops with simple reassignment over `.reduce()` for finding extreme values in performance-critical paths, especially for arrays that can grow very large.
diff --git a/apps/desktop/src/features/workspace/GrooveMap.tsx b/apps/desktop/src/features/workspace/GrooveMap.tsx
index 2745d4d7..2defcdd0 100644
--- a/apps/desktop/src/features/workspace/GrooveMap.tsx
+++ b/apps/desktop/src/features/workspace/GrooveMap.tsx
@@ -17,7 +17,14 @@ function GrooveMapComponent({ notes, isLoading }: GrooveMapProps) {
 
   // Find max offset to determine timeline width
   const maxTime = useMemo(() => {
-    return renderedNotes.reduce((max, n) => Math.max(max, n.offset), 10);
+    // Performance: Avoid function call overhead of .reduce() and Math.max for large arrays
+    let max = 10;
+    for (let i = 0; i < renderedNotes.length; i++) {
+      if (renderedNotes[i].offset > max) {
+        max = renderedNotes[i].offset;
+      }
+    }
+    return max;
   }, [renderedNotes]);
 
   // Unique pitches to determine vertical lanes (avoiding 88-key piano roll)