Mac Pro, Mac Mini, iMac, MacBook, MacBook Pro, iPad, Displays
Mac Pro Westmere Performance with Handbrake Video Encoding
The 12-core is about 20% faster than the 6-core, because Handbrake uses only about 9 cores.
Beta build vs regular
The August 30, 2010 build is about 9% faster than the 0.94 release version.
These are the settings used for testing.