Which OS X Release? with which benchmark? uncontended pthread_mutex was made significantly faster in OS X El Capitan (almost twice as fast as before), and on my own mac is only twice as slow as OSSpinLock, and OSSpinLock unlock is a store(lock, 0), where a mutex usually need an xchg or cmpxchg which amount for most of the 2x performance loss.<p>I very very much doubt that linux implementation is that different (I&#x27;m actually fairly confident pthread_mutex on linux and OS X El Capitan+ are mostly on par)