diff --git a/packages/agent-intelligence/src/services/orchestrator/OrchestrationState.ts b/packages/agent-intelligence/src/services/orchestrator/OrchestrationState.ts
index c8734e83..650a4240 100644
--- a/packages/agent-intelligence/src/services/orchestrator/OrchestrationState.ts
+++ b/packages/agent-intelligence/src/services/orchestrator/OrchestrationState.ts
@@ -70,7 +70,6 @@ export class OrchestrationStateManager {
     };
 
     const nodes = this.buildDependencyGraph();
-    const taskMap = new Map([...this.state.taskQueue, ...this.state.completedTasks].map((t) => [t.id, t]));
 
     for (const [taskId, node] of nodes) {
       if (node.status === 'complete') continue;
@@ -86,14 +85,14 @@ export class OrchestrationStateManager {
 
       if (pendingDeps.length === 0) {
         // Check if task has an assignee
-        const task = taskMap.get(taskId);
+        const task = this.state.taskQueue.find((t) => t.id === taskId);
         if (task?.assignee) {
           plan.ready.push(taskId);
         }
       } else {
         // Check for failed dependencies
         const failedDeps = pendingDeps.filter((depId) => {
-          const task = taskMap.get(depId);
+          const task = this.state.taskQueue.find((t) => t.id === depId);
           return task?.status === 'cancelled';
         });
 
diff --git a/src/components/code/DiffViewer.tsx b/src/components/code/DiffViewer.tsx
index 972919b2..3164f111 100644
--- a/src/components/code/DiffViewer.tsx
+++ b/src/components/code/DiffViewer.tsx
@@ -5,7 +5,7 @@
  * Supports unified and split view modes.
  */
 
-import { useState } from 'react';
+import { useMemo, useState } from 'react';
 import { ChevronDownIcon } from '@/components/icons';
 import { Text } from '@/components/ui';
 import { organicBorderRadius } from '@/lib/organic-styles';
@@ -95,9 +95,12 @@ export function DiffViewer({
 }: Readonly<DiffViewerProps>) {
   const [collapsed, setCollapsed] = useState(false);
 
-  const lines = diff || (oldContent && newContent ? parseDiff(oldContent, newContent) : []);
-  const additions = lines.filter((l) => l.type === 'add').length;
-  const deletions = lines.filter((l) => l.type === 'remove').length;
+  const lines = useMemo(
+    () => diff || (oldContent && newContent ? parseDiff(oldContent, newContent) : []),
+    [diff, oldContent, newContent]
+  );
+  const additions = useMemo(() => lines.filter((l) => l.type === 'add').length, [lines]);
+  const deletions = useMemo(() => lines.filter((l) => l.type === 'remove').length, [lines]);
 
   const getLineStyle = (type: DiffLine['type']) => {
     switch (type) {
diff --git a/src/components/code/__tests__/DiffViewer.perf.test.tsx b/src/components/code/__tests__/DiffViewer.perf.test.tsx
new file mode 100644
index 00000000..ef65bae6
--- /dev/null
+++ b/src/components/code/__tests__/DiffViewer.perf.test.tsx
@@ -0,0 +1,50 @@
+import { act, fireEvent, render, screen } from '@testing-library/react';
+import { DiffViewer } from '../DiffViewer';
+
+// Mock dependencies to isolate DiffViewer performance
+vi.mock('@/components/icons', () => ({
+  ChevronDownIcon: () => <span>ChevronDown</span>,
+}));
+
+vi.mock('@/components/ui', () => ({
+  // biome-ignore lint/suspicious/noExplicitAny: mock
+  Text: ({ children, ...props }: any) => <span {...props}>{children}</span>,
+}));
+
+vi.mock('@/lib/organic-styles', () => ({
+  organicBorderRadius: { card: {} },
+}));
+
+describe('DiffViewer Performance', () => {
+  it('measures re-render time with large diffs', async () => {
+    // Generate large content (~5000 lines) to make parsing expensive
+    const linesCount = 5000;
+    const oldContent = Array.from({ length: linesCount }, (_, i) => `original line ${i}`).join(
+      '\n'
+    );
+    const newContent = Array.from({ length: linesCount }, (_, i) => `modified line ${i}`).join(
+      '\n'
+    );
+
+    // Initial Render
+    const startRender = performance.now();
+    render(<DiffViewer oldContent={oldContent} newContent={newContent} filename="benchmark.ts" />);
+    const endRender = performance.now();
+    console.log(`[Benchmark] Initial render time: ${(endRender - startRender).toFixed(2)}ms`);
+
+    const button = screen.getByRole('button');
+
+    // Trigger re-render by collapsing
+    const startUpdate = performance.now();
+    await act(async () => {
+      fireEvent.click(button);
+    });
+    const endUpdate = performance.now();
+
+    const updateTime = endUpdate - startUpdate;
+    console.log(`[Benchmark] Re-render time (collapse): ${updateTime.toFixed(2)}ms`);
+
+    // Sanity check
+    expect(updateTime).toBeGreaterThan(0);
+  }, 10000);
+});