diff --git a/core/java/android/app/IActivityTaskManager.aidl b/core/java/android/app/IActivityTaskManager.aidl
index 37136a1..368a1bc 100644
--- a/core/java/android/app/IActivityTaskManager.aidl
+++ b/core/java/android/app/IActivityTaskManager.aidl
@@ -405,6 +405,14 @@
     void setDisablePreviewScreenshots(IBinder token, boolean disable);
 
     /**
+     * It should only be called from home activity to remove its outdated snapshot. The home
+     * snapshot is used to speed up entering home from screen off. If the content of home activity
+     * is significantly different from before taking the snapshot, then the home activity can use
+     * this method to avoid inconsistent transition.
+     */
+    void invalidateHomeTaskSnapshot(IBinder homeToken);
+
+    /**
      * Return the user id of last resumed activity.
      */
     int getLastResumedActivityUserId();
diff --git a/packages/SystemUI/shared/src/com/android/systemui/shared/system/ActivityManagerWrapper.java b/packages/SystemUI/shared/src/com/android/systemui/shared/system/ActivityManagerWrapper.java
index 70f8e15..deaafca 100644
--- a/packages/SystemUI/shared/src/com/android/systemui/shared/system/ActivityManagerWrapper.java
+++ b/packages/SystemUI/shared/src/com/android/systemui/shared/system/ActivityManagerWrapper.java
@@ -28,6 +28,7 @@
 import static android.app.WindowConfiguration.WINDOWING_MODE_UNDEFINED;
 
 import android.annotation.NonNull;
+import android.app.Activity;
 import android.app.ActivityManager;
 import android.app.ActivityManager.RecentTaskInfo;
 import android.app.ActivityManager.RunningTaskInfo;
@@ -161,6 +162,23 @@
     }
 
     /**
+     * Removes the outdated snapshot of home task.
+     */
+    public void invalidateHomeTaskSnapshot(final Activity homeActivity) {
+        mBackgroundExecutor.submit(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    ActivityTaskManager.getService().invalidateHomeTaskSnapshot(
+                            homeActivity.getActivityToken());
+                } catch (RemoteException e) {
+                    Log.w(TAG, "Failed to invalidate home snapshot", e);
+                }
+            }
+        });
+    }
+
+    /**
      * @return the activity label, badging if necessary.
      */
     public String getBadgedActivityLabel(ActivityInfo info, int userId) {
diff --git a/services/core/java/com/android/server/policy/PhoneWindowManager.java b/services/core/java/com/android/server/policy/PhoneWindowManager.java
index 8435a82..c05b704 100644
--- a/services/core/java/com/android/server/policy/PhoneWindowManager.java
+++ b/services/core/java/com/android/server/policy/PhoneWindowManager.java
@@ -157,6 +157,7 @@
 import android.os.StrictMode;
 import android.os.SystemClock;
 import android.os.SystemProperties;
+import android.os.Trace;
 import android.os.UEventObserver;
 import android.os.UserHandle;
 import android.os.VibrationEffect;
@@ -4603,6 +4604,7 @@
     public void screenTurningOn(final ScreenOnListener screenOnListener) {
         if (DEBUG_WAKEUP) Slog.i(TAG, "Screen turning on...");
 
+        Trace.asyncTraceBegin(Trace.TRACE_TAG_WINDOW_MANAGER, "screenTurningOn", 0 /* cookie */);
         updateScreenOffSleepToken(false);
         mDefaultDisplayPolicy.screenTurnedOn(screenOnListener);
 
@@ -4665,6 +4667,7 @@
         if (!mDefaultDisplayPolicy.finishScreenTurningOn()) {
             return; // Spurious or not ready yet.
         }
+        Trace.asyncTraceEnd(Trace.TRACE_TAG_WINDOW_MANAGER, "screenTurningOn", 0 /* cookie */);
 
         final boolean enableScreen;
         final boolean awake = mDefaultDisplayPolicy.isAwake();
diff --git a/services/core/java/com/android/server/wm/ActivityRecord.java b/services/core/java/com/android/server/wm/ActivityRecord.java
index bc2fa4e..59fb319 100644
--- a/services/core/java/com/android/server/wm/ActivityRecord.java
+++ b/services/core/java/com/android/server/wm/ActivityRecord.java
@@ -1640,6 +1640,17 @@
                 allowTaskSnapshot, activityCreated, fromRecents, snapshot);
 
         if (type == STARTING_WINDOW_TYPE_SNAPSHOT) {
+            if (isActivityTypeHome()) {
+                // The snapshot of home is only used once because it won't be updated while screen
+                // is on (see {@link TaskSnapshotController#screenTurningOff}).
+                mWmService.mTaskSnapshotController.removeSnapshotCache(task.mTaskId);
+                // TODO(b/9684093): Use more general condition to specify the case.
+                if (mDisplayContent.mAppTransition
+                        .getAppTransition() != WindowManager.TRANSIT_KEYGUARD_GOING_AWAY) {
+                    // Only use snapshot of home as starting window when unlocking.
+                    return false;
+                }
+            }
             return createSnapshot(snapshot);
         }
 
diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index 46c4d87..c405100 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -4572,6 +4572,17 @@
         }
     }
 
+    @Override
+    public void invalidateHomeTaskSnapshot(IBinder token) {
+        synchronized (mGlobalLock) {
+            final ActivityRecord r = ActivityRecord.isInStackLocked(token);
+            if (r == null || !r.isActivityTypeHome()) {
+                return;
+            }
+            mWindowManager.mTaskSnapshotController.removeSnapshotCache(r.getTask().mTaskId);
+        }
+    }
+
     /** Return the user id of the last resumed activity. */
     @Override
     public @UserIdInt
diff --git a/services/core/java/com/android/server/wm/TaskSnapshotCache.java b/services/core/java/com/android/server/wm/TaskSnapshotCache.java
index 5cbab5d..7b0d841 100644
--- a/services/core/java/com/android/server/wm/TaskSnapshotCache.java
+++ b/services/core/java/com/android/server/wm/TaskSnapshotCache.java
@@ -109,7 +109,7 @@
         removeRunningEntry(taskId);
     }
 
-    private void removeRunningEntry(int taskId) {
+    void removeRunningEntry(int taskId) {
         final CacheEntry entry = mRunningCache.get(taskId);
         if (entry != null) {
             mAppTaskMap.remove(entry.topApp);
diff --git a/services/core/java/com/android/server/wm/TaskSnapshotController.java b/services/core/java/com/android/server/wm/TaskSnapshotController.java
index c1a36c4..12b2845 100644
--- a/services/core/java/com/android/server/wm/TaskSnapshotController.java
+++ b/services/core/java/com/android/server/wm/TaskSnapshotController.java
@@ -171,22 +171,30 @@
     }
 
     void snapshotTasks(ArraySet<Task> tasks) {
+        snapshotTasks(mTmpTasks, false /* allowSnapshotHome */);
+    }
+
+    private void snapshotTasks(ArraySet<Task> tasks, boolean allowSnapshotHome) {
         for (int i = tasks.size() - 1; i >= 0; i--) {
             final Task task = tasks.valueAt(i);
-            final int mode = getSnapshotMode(task);
             final TaskSnapshot snapshot;
-            switch (mode) {
-                case SNAPSHOT_MODE_NONE:
-                    continue;
-                case SNAPSHOT_MODE_APP_THEME:
-                    snapshot = drawAppThemeSnapshot(task);
-                    break;
-                case SNAPSHOT_MODE_REAL:
-                    snapshot = snapshotTask(task);
-                    break;
-                default:
-                    snapshot = null;
-                    break;
+            final boolean snapshotHome = allowSnapshotHome && task.isActivityTypeHome();
+            if (snapshotHome) {
+                snapshot = snapshotTask(task);
+            } else {
+                switch (getSnapshotMode(task)) {
+                    case SNAPSHOT_MODE_NONE:
+                        continue;
+                    case SNAPSHOT_MODE_APP_THEME:
+                        snapshot = drawAppThemeSnapshot(task);
+                        break;
+                    case SNAPSHOT_MODE_REAL:
+                        snapshot = snapshotTask(task);
+                        break;
+                    default:
+                        snapshot = null;
+                        break;
+                }
             }
             if (snapshot != null) {
                 final GraphicBuffer buffer = snapshot.getSnapshot();
@@ -196,8 +204,11 @@
                             + buffer.getHeight());
                 } else {
                     mCache.putSnapshot(task, snapshot);
-                    mPersister.persistSnapshot(task.mTaskId, task.mUserId, snapshot);
-                    task.onSnapshotChanged(snapshot);
+                    // Don't persist or notify the change for the temporal snapshot.
+                    if (!snapshotHome) {
+                        mPersister.persistSnapshot(task.mTaskId, task.mUserId, snapshot);
+                        task.onSnapshotChanged(snapshot);
+                    }
                 }
             }
         }
@@ -450,6 +461,10 @@
         mPersister.onTaskRemovedFromRecents(taskId, userId);
     }
 
+    void removeSnapshotCache(int taskId) {
+        mCache.removeRunningEntry(taskId);
+    }
+
     /**
      * See {@link TaskSnapshotPersister#removeObsoleteFiles}
      */
@@ -485,7 +500,9 @@
                             mTmpTasks.add(task);
                         }
                     });
-                    snapshotTasks(mTmpTasks);
+                    // Allow taking snapshot of home when turning screen off to reduce the delay of
+                    // unlocking/waking to home.
+                    snapshotTasks(mTmpTasks, true /* allowSnapshotHome */);
                 }
             } finally {
                 listener.onScreenOff();