diff --git a/frontend/taskdeck-web/src/components/board/BoardSettingsModal.vue b/frontend/taskdeck-web/src/components/board/BoardSettingsModal.vue
index 519641f7e..2e658444b 100644
--- a/frontend/taskdeck-web/src/components/board/BoardSettingsModal.vue
+++ b/frontend/taskdeck-web/src/components/board/BoardSettingsModal.vue
@@ -21,6 +21,7 @@ const router = useRouter()
 // Form state
 const name = ref('')
 const description = ref('')
+const lifecycleActionInProgress = ref(false)
 
 // Watch for board changes
 watch(() => props.board, (newBoard) => {
@@ -30,9 +31,12 @@ watch(() => props.board, (newBoard) => {
   }
 }, { immediate: true })
 
-const lifecycleActionLabel = computed(() => (
-  props.board.isArchived ? 'Restore Board' : 'Move to Archive'
-))
+const lifecycleActionLabel = computed(() => {
+  if (lifecycleActionInProgress.value) {
+    return props.board.isArchived ? 'Restoring...' : 'Archiving...'
+  }
+  return props.board.isArchived ? 'Restore Board' : 'Move to Archive'
+})
 
 const lifecycleActionButtonClass = computed(() => (
   props.board.isArchived
@@ -80,21 +84,32 @@ async function handleLifecycleTransition() {
     return
   }
 
+  lifecycleActionInProgress.value = true
+
   try {
     if (shouldArchive) {
+      // Navigate away BEFORE clearing board state to prevent the mounted
+      // BoardView from re-rendering every computed (columns, cards, filters)
+      // as each piece of state is set to null/empty.  This was the root cause
+      // of the ~30-second freeze reported in #519 — sequential reactive
+      // mutations cascaded through dozens of watchers while the view was
+      // still mounted.
+      emit('updated')
+      emit('close')
+      await router.push('/boards')
+
+      // Run the store mutation after navigation so the old BoardView is
+      // already unmounted and its reactive subscriptions are torn down.
       await boardStore.deleteBoard(props.board.id)
     } else {
       await boardStore.updateBoard(props.board.id, { isArchived: false })
-    }
-
-    emit('updated')
-    emit('close')
-
-    if (shouldArchive) {
-      router.push('/boards')
+      emit('updated')
+      emit('close')
     }
   } catch (error) {
     console.error('Failed to update board lifecycle state:', error)
+  } finally {
+    lifecycleActionInProgress.value = false
   }
 }
 
@@ -188,6 +203,7 @@ useEscapeToClose(() => props.isOpen, handleClose)
           <button
             @click="handleLifecycleTransition"
             type="button"
+            :disabled="lifecycleActionInProgress"
             :class="lifecycleActionButtonClass"
           >
             {{ lifecycleActionLabel }}
diff --git a/frontend/taskdeck-web/src/store/board/boardCrudStore.ts b/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
index a2c87ad52..348b70da1 100644
--- a/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
+++ b/frontend/taskdeck-web/src/store/board/boardCrudStore.ts
@@ -139,16 +139,13 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
       state.error.value = null
       await boardsApi.deleteBoard(boardId)
 
-      // Remove from boards list
-      state.boards.value = state.boards.value.filter((b) => b.id !== boardId)
-
-      // Clear activeBoardId if the deleted board was the active selection
-      if (state.activeBoardId.value === boardId) {
-        state.activeBoardId.value = state.boards.value[0]?.id ?? null
-      }
-
-      // Clear current board if it's the one being deleted
-      if (state.currentBoard.value && state.currentBoard.value.id === boardId) {
+      // Clear detailed state for the current board before removing it from the
+      // main boards list. This prevents any watchers on the `boards` array
+      // from accidentally accessing stale detail state (like cards, labels, etc.)
+      // that belongs to the board being deleted. The primary performance fix
+      // for #519 is unmounting the BoardView before this action is called.
+      const isCurrent = state.currentBoard.value?.id === boardId
+      if (isCurrent) {
         state.currentBoard.value = null
         state.currentBoardCards.value = []
         state.currentBoardLabels.value = []
@@ -157,6 +154,15 @@ export function createBoardCrudActions(state: BoardState, helpers: BoardHelpers)
         state.editingCardId.value = null
       }
 
+      // Remove from boards list after clearing detail state so downstream
+      // watchers on `boards` do not attempt to read stale detail refs.
+      state.boards.value = state.boards.value.filter((b) => b.id !== boardId)
+
+      // Clear activeBoardId if the deleted board was the active selection
+      if (state.activeBoardId.value === boardId) {
+        state.activeBoardId.value = state.boards.value[0]?.id ?? null
+      }
+
       helpers.toast.success('Board archived successfully')
     } catch (e: unknown) {
       helpers.handleApiError(e, 'Failed to archive board')
diff --git a/frontend/taskdeck-web/src/tests/components/BoardSettingsModal.spec.ts b/frontend/taskdeck-web/src/tests/components/BoardSettingsModal.spec.ts
index 2d5edd619..e08ab10d1 100644
--- a/frontend/taskdeck-web/src/tests/components/BoardSettingsModal.spec.ts
+++ b/frontend/taskdeck-web/src/tests/components/BoardSettingsModal.spec.ts
@@ -215,11 +215,65 @@ describe('BoardSettingsModal', () => {
     expect(mockStore.deleteBoard).toHaveBeenCalledWith('board-1')
     expect(mockStore.updateBoard).not.toHaveBeenCalled()
     expect(wrapper.emitted('close')).toBeTruthy()
+    // Navigation happens before deleteBoard to prevent reactive cascade freeze (#519)
     expect(mockRouter.push).toHaveBeenCalledWith('/boards')
 
     confirmSpy.mockRestore()
   })
 
+  it('should navigate before deleting board to avoid reactive cascade freeze', async () => {
+    const confirmSpy = vi.spyOn(window, 'confirm').mockReturnValue(true)
+    const callOrder: string[] = []
+    mockRouter.push.mockImplementation(async () => { callOrder.push('navigate') })
+    mockStore.deleteBoard.mockImplementation(async () => { callOrder.push('delete') })
+
+    const wrapper = mount(BoardSettingsModal, {
+      props: {
+        board,
+        isOpen: true,
+      },
+    })
+
+    const archiveButton = wrapper
+      .findAll('button')
+      .find((btn) => btn.text().includes('Move to Archive'))
+    await archiveButton?.trigger('click')
+    await wrapper.vm.$nextTick()
+
+    expect(callOrder).toEqual(['navigate', 'delete'])
+
+    confirmSpy.mockRestore()
+  })
+
+  it('should disable lifecycle button while action is in progress', async () => {
+    const confirmSpy = vi.spyOn(window, 'confirm').mockReturnValue(true)
+    let resolvePush: () => void
+    mockRouter.push.mockReturnValue(new Promise<void>((resolve) => { resolvePush = resolve }))
+
+    const wrapper = mount(BoardSettingsModal, {
+      props: {
+        board,
+        isOpen: true,
+      },
+    })
+
+    const archiveButton = wrapper
+      .findAll('button')
+      .find((btn) => btn.text().includes('Move to Archive'))
+    void archiveButton?.trigger('click')
+    await wrapper.vm.$nextTick()
+    await wrapper.vm.$nextTick()
+
+    const buttonAfterClick = wrapper
+      .findAll('button')
+      .find((btn) => btn.text().includes('Archiving...'))
+    expect(buttonAfterClick?.exists()).toBe(true)
+    expect((buttonAfterClick?.element as HTMLButtonElement).disabled).toBe(true)
+
+    resolvePush!()
+    confirmSpy.mockRestore()
+  })
+
   it('should show restore action when board is archived', () => {
     const archivedBoard = { ...board, isArchived: true }