diff --git a/src/renderer/src/lib/agent-startup-delayed-delivery-perf.test.ts b/src/renderer/src/lib/agent-startup-delayed-delivery-perf.test.ts
new file mode 100644
index 000000000..3ea4a168b
--- /dev/null
+++ b/src/renderer/src/lib/agent-startup-delayed-delivery-perf.test.ts
@@ -0,0 +1,164 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { useAppStore } from '@/store'
+import {
+  queuePendingAgentStartupDelivery,
+  resetAgentStartupDelayedDeliveryForTests
+} from './agent-startup-delayed-delivery'
+
+const originalState = useAppStore.getState()
+const LEAF_ID = '11111111-1111-4111-8111-111111111111'
+
+function seedPendingState(agentLaunchConfigByPaneKey: Record<string, unknown> = {}): void {
+  useAppStore.setState({
+    tabsByWorktree: {
+      'wt-background': [
+        {
+          id: 'tab-background',
+          ptyId: null,
+          worktreeId: 'wt-background',
+          title: 'Agent',
+          customTitle: null,
+          color: null,
+          sortOrder: 0,
+          createdAt: 1
+        }
+      ]
+    },
+    pendingStartupByTabId: {
+      'tab-background': { launchToken: 'target-launch' }
+    },
+    agentLaunchConfigByPaneKey,
+    ptyIdsByTabId: { 'tab-background': [] },
+    terminalLayoutsByTabId: {}
+  } as never)
+}
+
+function bindPendingPty(): void {
+  useAppStore.setState({
+    agentLaunchConfigByPaneKey: {
+      [`tab-background:${LEAF_ID}`]: {
+        identity: {
+          tabId: 'tab-background',
+          leafId: LEAF_ID,
+          launchToken: 'target-launch'
+        }
+      }
+    },
+    ptyIdsByTabId: { 'tab-background': ['pty-background'] },
+    terminalLayoutsByTabId: {
+      'tab-background': {
+        root: { type: 'leaf', leafId: LEAF_ID },
+        activeLeafId: LEAF_ID,
+        expandedLeafId: null,
+        ptyIdsByLeafId: { [LEAF_ID]: 'pty-background' }
+      }
+    }
+  } as never)
+}
+
+function countedLaunchConfigs(count: number): {
+  reads: { value: number }
+  record: Record<string, unknown>
+} {
+  const reads = { value: 0 }
+  const record: Record<string, unknown> = {}
+  for (let index = 0; index < count; index += 1) {
+    Object.defineProperty(record, `other-pane-${index}`, {
+      enumerable: true,
+      get: () => {
+        reads.value += 1
+        return {
+          identity: {
+            tabId: `other-tab-${index}`,
+            launchToken: `other-launch-${index}`
+          }
+        }
+      }
+    })
+  }
+  return { reads, record }
+}
+
+afterEach(() => {
+  resetAgentStartupDelayedDeliveryForTests()
+  useAppStore.setState(originalState, true)
+})
+
+describe('delayed agent startup subscription', () => {
+  it('does not rescan launch metadata for unrelated store updates', () => {
+    const launchConfigs = countedLaunchConfigs(500)
+    seedPendingState(launchConfigs.record)
+
+    queuePendingAgentStartupDelivery({
+      worktreeId: 'wt-background',
+      tabId: 'tab-background',
+      launchToken: 'target-launch',
+      startup: {} as never,
+      deliver: vi.fn()
+    })
+    expect(launchConfigs.reads.value).toBe(500)
+
+    launchConfigs.reads.value = 0
+    for (let update = 0; update < 100; update += 1) {
+      useAppStore.setState({ activeView: update % 2 === 0 ? 'terminal' : 'settings' } as never)
+    }
+
+    expect(launchConfigs.reads.value).toBe(0)
+  })
+
+  it('delivers when launch registration, PTY ownership, and layout binding arrive', () => {
+    seedPendingState()
+    const deliver = vi.fn().mockResolvedValue(undefined)
+    const startup = {} as never
+    queuePendingAgentStartupDelivery({
+      worktreeId: 'wt-background',
+      tabId: 'tab-background',
+      launchToken: 'target-launch',
+      startup,
+      deliver
+    })
+
+    bindPendingPty()
+
+    expect(deliver).toHaveBeenCalledWith('tab-background', 'pty-background', startup)
+  })
+
+  it('drops a delivery when its tab is removed before PTY binding', () => {
+    seedPendingState()
+    const deliver = vi.fn().mockResolvedValue(undefined)
+    queuePendingAgentStartupDelivery({
+      worktreeId: 'wt-background',
+      tabId: 'tab-background',
+      launchToken: 'target-launch',
+      startup: {} as never,
+      deliver
+    })
+
+    useAppStore.setState({ tabsByWorktree: {} })
+    seedPendingState()
+    bindPendingPty()
+
+    expect(deliver).not.toHaveBeenCalled()
+  })
+
+  it('drops a delivery when a newer pending launch token replaces it', () => {
+    seedPendingState()
+    const deliver = vi.fn().mockResolvedValue(undefined)
+    queuePendingAgentStartupDelivery({
+      worktreeId: 'wt-background',
+      tabId: 'tab-background',
+      launchToken: 'target-launch',
+      startup: {} as never,
+      deliver
+    })
+
+    useAppStore.setState({
+      pendingStartupByTabId: {
+        'tab-background': { launchToken: 'newer-launch' }
+      }
+    } as never)
+    bindPendingPty()
+
+    expect(deliver).not.toHaveBeenCalled()
+  })
+})
diff --git a/src/renderer/src/lib/agent-startup-delayed-delivery.ts b/src/renderer/src/lib/agent-startup-delayed-delivery.ts
index 5ca13944b..2e38fad41 100644
--- a/src/renderer/src/lib/agent-startup-delayed-delivery.ts
+++ b/src/renderer/src/lib/agent-startup-delayed-delivery.ts
@@ -90,7 +90,33 @@ function ensurePendingAgentStartupSubscription(): void {
   if (unsubscribePendingAgentStartupDeliveries) {
     return
   }
-  unsubscribePendingAgentStartupDeliveries = useAppStore.subscribe(() => {
+  const initial = useAppStore.getState()
+  // Capture the individual references so the gate stays allocation-free and
+  // remains correct even if a subscribe adapter reuses its state object.
+  let previousTabs = initial.tabsByWorktree
+  let previousPendingStartups = initial.pendingStartupByTabId
+  let previousLaunchConfigs = initial.agentLaunchConfigByPaneKey
+  let previousPtyIds = initial.ptyIdsByTabId
+  let previousLayouts = initial.terminalLayoutsByTabId
+  unsubscribePendingAgentStartupDeliveries = useAppStore.subscribe((state) => {
+    // Why: a background workspace can stay unmounted indefinitely. Only these
+    // five immutable slices can change delivery eligibility; unrelated title,
+    // status, focus, and usage ticks must not rescan every launch registration.
+    if (
+      state.tabsByWorktree === previousTabs &&
+      state.pendingStartupByTabId === previousPendingStartups &&
+      state.agentLaunchConfigByPaneKey === previousLaunchConfigs &&
+      state.ptyIdsByTabId === previousPtyIds &&
+      state.terminalLayoutsByTabId === previousLayouts
+    ) {
+      return
+    }
+    // Update before flushing because delivery can synchronously write the store.
+    previousTabs = state.tabsByWorktree
+    previousPendingStartups = state.pendingStartupByTabId
+    previousLaunchConfigs = state.agentLaunchConfigByPaneKey
+    previousPtyIds = state.ptyIdsByTabId
+    previousLayouts = state.terminalLayoutsByTabId
     flushPendingAgentStartupDeliveries()
   })
 }