Federico Viticci testing his new MacBook Air 13″ with and without FileVault:

My Geekbench results (run with the latest version of the app available, at 64-bit, with system daemons-only running in the background) report two points more to the test performed when FileVault was turned on.

He also ran some nice “real world” tests and his conclusion is similar to mine: you don’t notice any performance difference. Here’s my advice with FileVault: turn it on and leave it on until you think to yourself “this computer is so slow that I need a new one.” Until you reach such a point there is no reason to have it off, that added security (including the upcoming remote wipe) is killer.

Posted by Ben Brooks