How to Monitor FPS (Frames Per Second) Live in Mac OS X with Quartz Debug
Whether testing performance of an application, Mac OS X animations, or just out of general curiosity, you can measure the refresh rate in Frames Per Second of onscreen actions and animations on the Mac by using a free developer tool from Apple called Quartz Debug.
Part of the Graphics Tools package of Xcode, Quartz Debug can also be downloaded separately if you have a developer login, and a simple action will enable the live FPS monitor, providing frame rate data in real-time.