Short-cut the call to Timer.run, to not go through standalone.

sdk/lib/io/timer_impl.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 // Timer heap implemented as a array-based binary heap[0].
 // This allows for O(1) `first`, O(log(n)) `remove`/`removeFirst` and O(log(n))
 // `add`.
 //
@@ skipping 110 matching lines @@
   // Disables the timer.
   static const int _NO_TIMER = -1;
 
   // Timers are ordered by wakeup time.
   static _TimerHeap _heap = new _TimerHeap();
   static _Timer _firstZeroTimer;
   static _Timer _lastZeroTimer;
   static int _idCount = 0;
 
   static RawReceivePort _receivePort;
+  static SendPort _sendPort;
   static bool _handlingCallbacks = false;
 
   Function _callback;
   int _milliSeconds;
   int _wakeupTime = 0;
   var _indexOrNext;
   int _id = -1;
 
   static Timer _createTimer(void callback(Timer timer),
                             int milliSeconds,
@@ skipping 58 matching lines @@
   void _advanceWakeupTime() {
     assert(_milliSeconds >= 0);
     _wakeupTime += _milliSeconds;
   }
 
   // Adds a timer to the timer list. Timers with the same wakeup time are
   // enqueued in order and notified in FIFO order.
   bool _addTimerToHeap() {
     if (_wakeupTime == 0) {
       if (_firstZeroTimer == null) {
         _lastZeroTimer = _firstZeroTimer = this;

[Ivan Posva, 2014/02/05 16:54:46]

_lastZeroTimer = this;
_firstZeroTimer = this;

The way it is written is not immediately readable as it might also mean:
_lastZeroTimer = _firstZeroTimer == this;
Where the second = was dropped.

         return true;
       } else {
         _lastZeroTimer = _lastZeroTimer._indexOrNext = this;
         return false;
       }
     } else {
       _id = _idCount++;
       _heap.add(this);
       return _firstZeroTimer == null && _heap.isFirst(this);
     }
@@ skipping 14 matching lines @@
       if (_receivePort != null) {
         _EventHandler._sendData(null, _receivePort, _NO_TIMER);
         _shutdownTimerHandler();
       }
     } else {
       if (_receivePort == null) {
         // Create a receive port and register a message handler for the timer
         // events.
         _createTimerHandler();
       }
-      _EventHandler._sendData(null,
-                              _receivePort,
-                              _firstZeroTimer != null ?
-                                  0 : _heap.first._wakeupTime);
+      if (_firstZeroTimer != null) {
+        _sendPort.send(null);
+      } else {
+        _EventHandler._sendData(null,
+                                _receivePort,
+                                _heap.first._wakeupTime);
+      }
     }
   }
 
   static void _handleTimeout(_) {
     int currentTime = new DateTime.now().millisecondsSinceEpoch;
     // Collect all pending timers.
     var timer = _firstZeroTimer;
     var nextTimer = _lastZeroTimer;
     _firstZeroTimer = _lastZeroTimer = null;

[Ivan Posva, 2014/02/05 16:54:46]

ditto

     while (_heap.isNotEmpty && _heap.first._wakeupTime <= currentTime) {
       var next = _heap.removeFirst();
       if (timer == null) {
         nextTimer = timer = next;

[Ivan Posva, 2014/02/05 16:54:46]

ditto. Here and other places.

       } else {
         nextTimer = nextTimer._indexOrNext = next;
       }
     }
 
     // Trigger all of the pending timers. New timers added as part of the
     // callbacks will be enqueued now and notified in the next spin at the
     // earliest.
     _handlingCallbacks = true;
     try {
@@ skipping 22 matching lines @@
       _handlingCallbacks = false;
       _notifyEventHandler();
     }
   }
 
   // Creates a receive port and registers the timer handler on that
   // receive port.
   static void _createTimerHandler() {
     if(_receivePort == null) {
       _receivePort = new RawReceivePort(_handleTimeout);
+      _sendPort = _receivePort.sendPort;
     }
   }
 
   static void _shutdownTimerHandler() {
     _receivePort.close();
     _receivePort = null;
   }
 }
 
 // Provide a closure which will allocate a Timer object to be able to hook
 // up the Timer interface in dart:isolate with the implementation here.
 _getTimerFactoryClosure() {
   return (int milliSeconds, void callback(Timer timer), bool repeating) {
     if (repeating) {
       return new _Timer.periodic(milliSeconds, callback);
     }
     return new _Timer(milliSeconds, callback);
   };
 }