⚡ Bolt: computeTaskMetrics 배열 순회 최적화

.jules/bolt.md

@@ -4,3 +4,6 @@
 ## 2026-07-12 - Optimize renderTaskRow DOM allocations
 **Learning:** Caching unattached template nodes and instantiating them via `.cloneNode(false)` reduces DOM instantiation overhead in O(N) render loops significantly.
 **Action:** Apply this optimization to other hot-path rendering elements such as rows, cells, and stack containers.
+## 2026-08-22 - Array reduce/forEach 및 Map 오버헤드 최적화
+**Learning:** computeTaskMetrics와 같이 자주 호출되는 O(N) 순회 로직에서 JS 내장 배열 메서드(reduce, forEach)와 Map을 사용하면 콜백 할당, GC, 해시 검색 오버헤드로 인해 성능 저하가 발생합니다.
+**Action:** 성능이 중요한 반복문에서는 일반 for 루프와 TypedArray(Int32Array)를 사용하여 JS 엔진 오버헤드를 최소화합니다.

app.js

@@ -1370,21 +1370,29 @@ function validateDateRange(startLabel, startValue, endLabel, endValue, errors) {
 }
 
 function computeTaskMetrics() {
-  // ⚡ Bolt: Cache durationDays during total calculation to avoid recalculating for every task
-  const durationCache = new Map();
-  const totalDays = state.tasks.reduce((sum, task) => {
+  const length = state.tasks.length;
+  // ⚡ Bolt: Use Int32Array to avoid object allocation and GC overhead for numeric caching
+  const durations = new Int32Array(length);
+  let totalDays = 0;
+
+  // ⚡ Bolt: Replace Array.reduce with a standard for loop to eliminate callback allocation overhead
+  for (let i = 0; i < length; i++) {
+    const task = state.tasks[i];
     const duration = calculateDurationDays(task.plannedStartDate, task.plannedEndDate);
-    durationCache.set(task.id, duration);
-    return sum + duration;
-  }, 0);
+    durations[i] = duration;
+    totalDays += duration;
+  }
 
   const baseDate = state.baseDate;
   const byTask = new Map();
   let totalWeightedPlannedRatio = 0;
   let totalWeightedActualRatio = 0;
 
-  state.tasks.forEach((task) => {
-    const durationDays = durationCache.get(task.id);
+  // ⚡ Bolt: Replace Array.forEach with a standard for loop to eliminate callback allocation overhead
+  for (let i = 0; i < length; i++) {
+    const task = state.tasks[i];
+    // ⚡ Bolt: Avoid Map hash lookup for durations
+    const durationDays = durations[i];
     const weightRatio = totalDays > 0 ? durationDays / totalDays : 0;
     const plannedProgressRatio = calculatePlannedProgressRatio(baseDate, task.plannedStartDate, task.plannedEndDate, durationDays);
     const actualProgressRatio = (ACTUAL_PROGRESS_MAP[task.actualProgressStatus] || 0) / 100;
@@ -1408,7 +1416,7 @@ function computeTaskMetrics() {
       plannedDateWarning,
       actualDateWarning
     });
-  });
+  }
 
   return {
     totalDays,