--- a/browser/modules/SchedulePressure.jsm
+++ b/browser/modules/SchedulePressure.jsm
@@ -114,13 +114,15 @@ this.SchedulePressure = {
    */
   stopMonitoring(window) {
     function removeFromMapAndCancelTimeout(map, cancelFn) {
       if (map.has(window)) {
         cancelFn(map.get(window));
         map.delete(window);
       }
     }
+
+    TelemetryStopwatch.cancel("FX_SCHEDULE_PRESSURE_IDLE_SAMPLE_MS", window);
     removeFromMapAndCancelTimeout(this._setTimeoutWeakMap, window.clearTimeout);
     removeFromMapAndCancelTimeout(this._idleCallbackWeakMap, window.cancelIdleCallback);
     removeFromMapAndCancelTimeout(this._telemetryCallbackWeakMap, window.cancelIdleCallback);
   },
 };