i'm guessing you're talking about a discrete graphics card right?

i can't really give you an answer on this, but if i had to guess i'd say it works better on anything but radeon cards(but then again are radeon cards supported on macs nowadays?)

also, not exactly the same, but still interesting measurements.

http://www.phoronix.com/scan.php?page=article&item=ubuntu130...

valve worked closely with nvidia and intel to improve the performance and compliance of the drivers. check this out for example http://blogs.valvesoftware.com/linux/faster-zombies/