diff --git a/quickstep/src/com/android/quickstep/RecentTasksList.java b/quickstep/src/com/android/quickstep/RecentTasksList.java
index 2d9c56f..70b4f20 100644
--- a/quickstep/src/com/android/quickstep/RecentTasksList.java
+++ b/quickstep/src/com/android/quickstep/RecentTasksList.java
@@ -40,21 +40,20 @@
 /**
  * Manages the recent task list from the system, caching it as necessary.
  */
-@TargetApi(Build.VERSION_CODES.P)
+@TargetApi(Build.VERSION_CODES.R)
 public class RecentTasksList extends TaskStackChangeListener {
 
+    private static final TaskLoadResult INVALID_RESULT = new TaskLoadResult(-1, false, 0);
+
     private final KeyguardManagerCompat mKeyguardManager;
     private final LooperExecutor mMainThreadExecutor;
     private final ActivityManagerWrapper mActivityManagerWrapper;
 
     // The list change id, increments as the task list changes in the system
     private int mChangeId;
-    // The last change id when the list was last loaded completely, must be <= the list change id
-    private int mLastLoadedId;
-    // The last change id was loaded with keysOnly  = true
-    private boolean mLastLoadHadKeysOnly;
 
-    ArrayList<Task> mTasks = new ArrayList<>();
+    private TaskLoadResult mResultsBg = INVALID_RESULT;
+    private TaskLoadResult mResultsUi = INVALID_RESULT;
 
     public RecentTasksList(LooperExecutor mainThreadExecutor,
             KeyguardManagerCompat keyguardManager, ActivityManagerWrapper activityManagerWrapper) {
@@ -71,7 +70,7 @@
     public void getTaskKeys(int numTasks, Consumer<ArrayList<Task>> callback) {
         // Kick off task loading in the background
         UI_HELPER_EXECUTOR.execute(() -> {
-            ArrayList<Task> tasks = loadTasksInBackground(numTasks, true /* loadKeysOnly */);
+            ArrayList<Task> tasks = loadTasksInBackground(numTasks, -1, true /* loadKeysOnly */);
             mMainThreadExecutor.execute(() -> callback.accept(tasks));
         });
     }
@@ -85,26 +84,30 @@
      */
     public synchronized int getTasks(boolean loadKeysOnly, Consumer<ArrayList<Task>> callback) {
         final int requestLoadId = mChangeId;
-        Runnable resultCallback = callback == null
-                ? () -> { }
-                : () -> callback.accept(copyOf(mTasks));
-
-        if (mLastLoadedId == mChangeId && (!mLastLoadHadKeysOnly || loadKeysOnly)) {
+        if (mResultsUi.isValidForRequest(requestLoadId, loadKeysOnly)) {
             // The list is up to date, send the callback on the next frame,
             // so that requestID can be returned first.
-            mMainThreadExecutor.post(resultCallback);
+            if (callback != null) {
+                // Copy synchronously as the changeId might change by next frame
+                ArrayList<Task> result = copyOf(mResultsUi);
+                mMainThreadExecutor.post(() -> callback.accept(result));
+            }
+
             return requestLoadId;
         }
 
         // Kick off task loading in the background
         UI_HELPER_EXECUTOR.execute(() -> {
-            ArrayList<Task> tasks = loadTasksInBackground(Integer.MAX_VALUE, loadKeysOnly);
-
+            if (!mResultsBg.isValidForRequest(requestLoadId, loadKeysOnly)) {
+                mResultsBg = loadTasksInBackground(Integer.MAX_VALUE, requestLoadId, loadKeysOnly);
+            }
+            TaskLoadResult loadResult = mResultsBg;
             mMainThreadExecutor.execute(() -> {
-                mTasks = tasks;
-                mLastLoadedId = requestLoadId;
-                mLastLoadHadKeysOnly = loadKeysOnly;
-                resultCallback.run();
+                mResultsUi = loadResult;
+                if (callback != null) {
+                    ArrayList<Task> result = copyOf(mResultsUi);
+                    callback.accept(result);
+                }
             });
         });
 
@@ -119,8 +122,8 @@
     }
 
     @Override
-    public synchronized void onTaskStackChanged() {
-        mChangeId++;
+    public void onTaskStackChanged() {
+        invalidateLoadedTasks();
     }
 
     @Override
@@ -131,22 +134,28 @@
         // callback (those are for changes to the active tasks), but the task list is still updated,
         // so we should also invalidate the change id to ensure we load a new list instead of 
         // reusing a stale list.
-        mChangeId++;
+        invalidateLoadedTasks();
     }
 
     @Override
     public void onTaskRemoved(int taskId) {
-        mTasks = loadTasksInBackground(Integer.MAX_VALUE, false);
+        invalidateLoadedTasks();
     }
 
+
     @Override
-    public synchronized void onActivityPinned(String packageName, int userId, int taskId,
-            int stackId) {
-        mChangeId++;
+    public void onActivityPinned(String packageName, int userId, int taskId, int stackId) {
+        invalidateLoadedTasks();
     }
 
     @Override
     public synchronized void onActivityUnpinned() {
+        invalidateLoadedTasks();
+    }
+
+    private synchronized void invalidateLoadedTasks() {
+        UI_HELPER_EXECUTOR.execute(() -> mResultsBg = INVALID_RESULT);
+        mResultsUi = INVALID_RESULT;
         mChangeId++;
     }
 
@@ -154,9 +163,8 @@
      * Loads and creates a list of all the recent tasks.
      */
     @VisibleForTesting
-    ArrayList<Task> loadTasksInBackground(int numTasks, boolean loadKeysOnly) {
+    TaskLoadResult loadTasksInBackground(int numTasks, int requestId, boolean loadKeysOnly) {
         int currentUserId = Process.myUserHandle().getIdentifier();
-        ArrayList<Task> allTasks = new ArrayList<>();
         List<ActivityManager.RecentTaskInfo> rawTasks =
                 mActivityManagerWrapper.getRecentTasks(numTasks, currentUserId);
         // The raw tasks are given in most-recent to least-recent order, we need to reverse it
@@ -173,6 +181,7 @@
             }
         };
 
+        TaskLoadResult allTasks = new TaskLoadResult(requestId, loadKeysOnly, rawTasks.size());
         for (ActivityManager.RecentTaskInfo rawTask : rawTasks) {
             Task.TaskKey taskKey = new Task.TaskKey(rawTask);
             Task task;
@@ -197,4 +206,22 @@
         }
         return newTasks;
     }
+
+    private static class TaskLoadResult extends ArrayList<Task> {
+
+        final int mId;
+
+        // If the result was loaded with keysOnly  = true
+        final boolean mKeysOnly;
+
+        TaskLoadResult(int id, boolean keysOnly, int size) {
+            super(size);
+            mId = id;
+            mKeysOnly = keysOnly;
+        }
+
+        boolean isValidForRequest(int requestId, boolean loadKeysOnly) {
+            return mId == requestId && (!mKeysOnly || loadKeysOnly);
+        }
+    }
 }
\ No newline at end of file
diff --git a/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java b/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java
index 34eb7f8..79ddf7a 100644
--- a/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java
+++ b/quickstep/tests/src/com/android/quickstep/RecentTasksListTest.java
@@ -58,9 +58,9 @@
     }
 
     @Test
-    public void onTaskRemoved_reloadsAllTasks() {
+    public void onTaskRemoved_doesNotFetchTasks() {
         mRecentTasksList.onTaskRemoved(0);
-        verify(mockActivityManagerWrapper, times(1))
+        verify(mockActivityManagerWrapper, times(0))
                 .getRecentTasks(anyInt(), anyInt());
     }
 
@@ -77,7 +77,7 @@
         when(mockActivityManagerWrapper.getRecentTasks(anyInt(), anyInt()))
                 .thenReturn(Collections.singletonList(recentTaskInfo));
 
-        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, true);
+        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, -1, true);
 
         assertEquals(1, taskList.size());
         assertNull(taskList.get(0).taskDescription.getLabel());
@@ -91,7 +91,7 @@
         when(mockActivityManagerWrapper.getRecentTasks(anyInt(), anyInt()))
                 .thenReturn(Collections.singletonList(recentTaskInfo));
 
-        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, false);
+        List<Task> taskList = mRecentTasksList.loadTasksInBackground(Integer.MAX_VALUE, -1, false);
 
         assertEquals(1, taskList.size());
         assertEquals(taskDescription, taskList.get(0).taskDescription.getLabel());