diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..e69de29
diff --git a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
index 35486b8..28c4229 100644
--- a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
+++ b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/[sessionId]/route.ts
@@ -43,9 +43,16 @@ export async function GET(
       return forbiddenByRole(access.role, '본인 세션만 열람 가능')
     }
 
-    const totalInput = session.usageRecords.reduce((sum, r) => sum + r.inputTokens, 0)
-    const totalOutput = session.usageRecords.reduce((sum, r) => sum + r.outputTokens, 0)
-    const totalCost = session.usageRecords.reduce((sum, r) => sum + (r.estimatedCostUsd ?? 0), 0)
+    // Performance Optimization: Combine 3 reduce calls into a single loop to avoid multiple iterations
+    // over potentially large usageRecords datasets.
+    let totalInput = 0;
+    let totalOutput = 0;
+    let totalCost = 0;
+    for (const r of session.usageRecords) {
+      totalInput += r.inputTokens;
+      totalOutput += r.outputTokens;
+      totalCost += (r.estimatedCostUsd ?? 0);
+    }
 
     const usageTimeline: SessionTimelineUsage[] = session.usageRecords.map((r) => ({
       timestamp: r.timestamp.toISOString(),
diff --git a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
index 25fbe70..297e14c 100644
--- a/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
+++ b/packages/web/src/app/api/orgs/[orgSlug]/dashboard/sessions/route.ts
@@ -33,13 +33,22 @@ const sessionInclude = {
 type SessionWithInclude = Prisma.ClaudeSessionGetPayload<{ include: typeof sessionInclude }>
 
 function getSessionTotals(session: SessionWithInclude) {
+  // Performance Optimization: Combine 3 reduce calls into a single loop to avoid multiple iterations
+  // over potentially large usageRecords datasets.
+  let inputTokens = 0;
+  let outputTokens = 0;
+  let estimatedCostUsd = 0;
+
+  for (const r of session.usageRecords) {
+    inputTokens += r.inputTokens;
+    outputTokens += r.outputTokens;
+    estimatedCostUsd += (r.estimatedCostUsd ?? 0);
+  }
+
   return {
-    inputTokens: session.usageRecords.reduce((sum, r) => sum + r.inputTokens, 0),
-    outputTokens: session.usageRecords.reduce((sum, r) => sum + r.outputTokens, 0),
-    estimatedCostUsd: session.usageRecords.reduce(
-      (sum, r) => sum + (r.estimatedCostUsd ?? 0),
-      0,
-    ),
+    inputTokens,
+    outputTokens,
+    estimatedCostUsd,
   }
 }