diff --git a/desktop/src/components/layout/Sidebar.test.tsx b/desktop/src/components/layout/Sidebar.test.tsx
index b058f593..0a2453f2 100644
--- a/desktop/src/components/layout/Sidebar.test.tsx
+++ b/desktop/src/components/layout/Sidebar.test.tsx
@@ -1,6 +1,7 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { act, cleanup, fireEvent, render, screen, waitFor, within } from '@testing-library/react'
 import '@testing-library/jest-dom'
+import { Profiler, type ProfilerOnRenderCallback } from 'react'
 
 const desktopUiPreferencesApiMock = vi.hoisted(() => ({
   getPreferences: vi.fn(),
@@ -1313,4 +1314,195 @@ describe('Sidebar', () => {
       value: originalVisibility,
     })
   })
+
+  describe('streaming optimization', () => {
+    it('does not re-render when only streamingText changes during token streaming', async () => {
+      const now = new Date().toISOString()
+      useSessionStore.setState({
+        sessions: [makeSession('session-1', 'Test Session', '/workspace/alpha', now)],
+      })
+      useChatStore.setState({
+        sessions: {
+          'session-1': makeChatSessionState({ chatState: 'idle', streamingText: '' }),
+        },
+      })
+
+      const renders: string[] = []
+      const onRender: ProfilerOnRenderCallback = (_, phase) => { renders.push(phase) }
+
+      render(
+        <Profiler id="stream-text" onRender={onRender}>
+          <Sidebar />
+        </Profiler>,
+      )
+
+      await act(async () => { await Promise.resolve() })
+      await act(async () => { await Promise.resolve() })
+      const initialCount = renders.length
+
+      // Simulate streaming token flush: only streamingText changes,
+      // creating a new top-level sessions reference (as updateSessionIn does)
+      act(() => {
+        const prev = useChatStore.getState().sessions
+        const session = prev['session-1']
+        useChatStore.setState({
+          sessions: { ...prev, 'session-1': { ...session, streamingText: 'Hello world' } },
+        })
+      })
+
+      expect(renders.length).toBe(initialCount)
+    })
+
+    it('does not re-render across multiple rapid streamingText updates', async () => {
+      const now = new Date().toISOString()
+      useSessionStore.setState({
+        sessions: [makeSession('session-1', 'Test Session', '/workspace/alpha', now)],
+      })
+      useChatStore.setState({
+        sessions: {
+          'session-1': makeChatSessionState({ chatState: 'idle', streamingText: '' }),
+        },
+      })
+
+      const renders: string[] = []
+      const onRender: ProfilerOnRenderCallback = (_, phase) => { renders.push(phase) }
+
+      render(
+        <Profiler id="stream-multi" onRender={onRender}>
+          <Sidebar />
+        </Profiler>,
+      )
+
+      await act(async () => { await Promise.resolve() })
+      await act(async () => { await Promise.resolve() })
+      const initialCount = renders.length
+
+      // Simulate 5 rapid token flushes (as the 50ms interval would produce)
+      for (let i = 0; i < 5; i++) {
+        act(() => {
+          const prev = useChatStore.getState().sessions
+          const session = prev['session-1']
+          useChatStore.setState({
+            sessions: {
+              ...prev,
+              'session-1': { ...session, streamingText: session.streamingText + ' token' + i },
+            },
+          })
+        })
+      }
+
+      expect(renders.length).toBe(initialCount)
+    })
+
+    it('does not re-render when only elapsedSeconds changes', async () => {
+      const now = new Date().toISOString()
+      useSessionStore.setState({
+        sessions: [makeSession('session-1', 'Test Session', '/workspace/alpha', now)],
+      })
+      useChatStore.setState({
+        sessions: {
+          'session-1': makeChatSessionState({ chatState: 'idle', elapsedSeconds: 0 }),
+        },
+      })
+
+      const renders: string[] = []
+      const onRender: ProfilerOnRenderCallback = (_, phase) => { renders.push(phase) }
+
+      render(
+        <Profiler id="elapsed-seconds" onRender={onRender}>
+          <Sidebar />
+        </Profiler>,
+      )
+
+      await act(async () => { await Promise.resolve() })
+      await act(async () => { await Promise.resolve() })
+      const initialCount = renders.length
+
+      act(() => {
+        const prev = useChatStore.getState().sessions
+        const session = prev['session-1']
+        useChatStore.setState({
+          sessions: { ...prev, 'session-1': { ...session, elapsedSeconds: 42 } },
+        })
+      })
+
+      expect(renders.length).toBe(initialCount)
+    })
+
+    it('re-renders and shows running indicator when chatState transitions to streaming', async () => {
+      const now = new Date().toISOString()
+      useSessionStore.setState({
+        sessions: [makeSession('session-1', 'Test Session', '/workspace/alpha', now)],
+      })
+      useChatStore.setState({
+        sessions: {
+          'session-1': makeChatSessionState({ chatState: 'idle' }),
+        },
+      })
+
+      const renders: string[] = []
+      const onRender: ProfilerOnRenderCallback = (_, phase) => { renders.push(phase) }
+
+      render(
+        <Profiler id="chatstate-on" onRender={onRender}>
+          <Sidebar />
+        </Profiler>,
+      )
+
+      await act(async () => { await Promise.resolve() })
+      await act(async () => { await Promise.resolve() })
+
+      expect(screen.queryByLabelText('Session running')).not.toBeInTheDocument()
+      const countBefore = renders.length
+
+      act(() => {
+        const prev = useChatStore.getState().sessions
+        const session = prev['session-1']
+        useChatStore.setState({
+          sessions: { ...prev, 'session-1': { ...session, chatState: 'streaming' } },
+        })
+      })
+
+      expect(renders.length).toBeGreaterThan(countBefore)
+      expect(screen.getByLabelText('Session running')).toBeInTheDocument()
+    })
+
+    it('re-renders and hides running indicator when chatState transitions back to idle', async () => {
+      const now = new Date().toISOString()
+      useSessionStore.setState({
+        sessions: [makeSession('session-1', 'Test Session', '/workspace/alpha', now)],
+      })
+      useChatStore.setState({
+        sessions: {
+          'session-1': makeChatSessionState({ chatState: 'streaming' }),
+        },
+      })
+
+      const renders: string[] = []
+      const onRender: ProfilerOnRenderCallback = (_, phase) => { renders.push(phase) }
+
+      render(
+        <Profiler id="chatstate-off" onRender={onRender}>
+          <Sidebar />
+        </Profiler>,
+      )
+
+      await act(async () => { await Promise.resolve() })
+      await act(async () => { await Promise.resolve() })
+
+      expect(screen.getByLabelText('Session running')).toBeInTheDocument()
+      const countBefore = renders.length
+
+      act(() => {
+        const prev = useChatStore.getState().sessions
+        const session = prev['session-1']
+        useChatStore.setState({
+          sessions: { ...prev, 'session-1': { ...session, chatState: 'idle' } },
+        })
+      })
+
+      expect(renders.length).toBeGreaterThan(countBefore)
+      expect(screen.queryByLabelText('Session running')).not.toBeInTheDocument()
+    })
+  })
 })
diff --git a/desktop/src/components/layout/Sidebar.tsx b/desktop/src/components/layout/Sidebar.tsx
index c6080879..f6389f2f 100644
--- a/desktop/src/components/layout/Sidebar.tsx
+++ b/desktop/src/components/layout/Sidebar.tsx
@@ -5,10 +5,10 @@ import { useUIStore } from '../../stores/uiStore'
 import { useTranslation, type TranslationKey } from '../../i18n'
 import { ConfirmDialog } from '../shared/ConfirmDialog'
 import { GlobalSearchModal } from '../search/GlobalSearchModal'
-import { FindInPageModal } from '../search/FindInPageModal'
 import type { SessionListItem } from '../../types/session'
 import { useTabStore, SETTINGS_TAB_ID, SCHEDULED_TAB_ID, MARKET_TAB_ID } from '../../stores/tabStore'
 import { useChatStore } from '../../stores/chatStore'
+import { useShallow } from 'zustand/react/shallow'
 import { useOpenTargetStore } from '../../stores/openTargetStore'
 import { desktopUiPreferencesApi, type SidebarProjectPreferences } from '../../api/desktopUiPreferences'
 import { getDesktopHost } from '../../lib/desktopHost'
@@ -70,7 +70,14 @@ export function Sidebar({ isMobile = false, onRequestClose }: SidebarProps) {
   const closeModal = useUIStore((s) => s.closeModal)
   const activeTabId = useTabStore((s) => s.activeTabId)
   const tabs = useTabStore((s) => s.tabs)
-  const chatSessions = useChatStore((s) => s.sessions)
+  const chatRunningSessionIds = useChatStore(useShallow((s) =>
+    Object.entries(s.sessions)
+      .filter(([, st]) =>
+        st.chatState !== 'idle' || hasRunningBackgroundTasks(st.backgroundAgentTasks),
+      )
+      .map(([id]) => id)
+      .sort(),
+  ))
   const closeTab = useTabStore((s) => s.closeTab)
   const disconnectSession = useChatStore((s) => s.disconnectSession)
   const [contextMenu, setContextMenu] = useState<{ id: string; x: number; y: number } | null>(null)
@@ -137,17 +144,12 @@ export function Sidebar({ isMobile = false, onRequestClose }: SidebarProps) {
     [sessions],
   )
   const runningSessionIds = useMemo(() => {
-    const ids = new Set<string>()
+    const ids = new Set<string>(chatRunningSessionIds)
     for (const tab of tabs) {
       if (tab.type === 'session' && tab.status === 'running') ids.add(tab.sessionId)
     }
-    for (const [sessionId, sessionState] of Object.entries(chatSessions)) {
-      if (sessionState.chatState !== 'idle' || hasRunningBackgroundTasks(sessionState.backgroundAgentTasks)) {
-        ids.add(sessionId)
-      }
-    }
     return ids
-  }, [chatSessions, tabs])
+  }, [chatRunningSessionIds, tabs])
   const pendingBatchDeleteSessions = useMemo(
     () => (pendingBatchDeleteSessionIds ?? [])
       .map((sessionId) => sessionsById.get(sessionId))
@@ -1222,7 +1224,6 @@ export function Sidebar({ isMobile = false, onRequestClose }: SidebarProps) {
       />
 
       <GlobalSearchModal open={activeModal === 'globalSearch'} onClose={closeModal} />
-      <FindInPageModal open={activeModal === 'findInPage'} onClose={closeModal} />
     </aside>
   )
 }