OSX's kernel comes with built in kernel tracing. Reading these traces can be incredibly helpful when dealing with mysterious performance problems. However, the trace utility does not ship with OSX, and even when you have it, its not very obvious how to use it.
This project downloads and compiles the OSX trace utility for you and wraps it so that it is stupid easy:
./osx-trace record my_trace.trace
Press control-C to finish recording.