Synchronized, NSLock, pthread, OSSpinLock comparative performance

Just ran this on my macbook pro core i7:

  NSLock: 3.364240 sec
  NSLock+IMP Cache: 2.772781 sec
  pthread_mutex: 1.733382 sec
  OSSpinlock: 0.323426 sec
  @synchronized: 4.250744 sec
  isMainThread: 0.373637 sec
  myDummy++: 0.063998 sec

The last two are [NSThread isMainThread], and a simple increment of a static variable. And same test on the iPhone 4s:

  NSLock: 21.619565 sec
  NSLock+IMP Cache: 18.740027 sec
  pthread_mutex: 11.585992 sec
  OSSpinlock: 3.576578 sec
  @synchronized: 28.453087 sec
  isMainThread: 2.662025 sec
  myDummy++: 0.634946 sec