I installed F1 2011 on Windows 7 64 bit on a 2011 Mac Mini (natively via Boot Camp). It's a 2.5Ghz i5 with 4GB DDR3 RAM and a Radeon HD 6630M gfx card.
I had the settings at Medium, and the game ran fine, Fraps reporting 50-60fps, but after 1 or 2 laps, the game became "jerky" or "stuttery". Not totally unplayable, but very noticeable and annoying. Thing is, the Fraps reported framerate was still fine.
I dropped the settings to Low, and again Fraps reported a decent frame rate, and the game was fine for a lap or so, then the same thing happened.
Thanks, but after some Googling I may have found a workaround - there's a hidden folder called C:\ProgramData\Codemasters\F1 2011\<username>\DataCache\Replay. Inside there's a 2GB+ file which contains a file that the game uses to constantly write a real-time replay too.
Apparently if you move this file to a different drive and replace it with a symlink, or make the file read-only, this can help solve the stuttering - it's due to this constant writing to the same drive the game is installed out that causes the stutter. Obviously making the file read-only means you lose the ability to view replays in the game, but that was no big deal for me.