Even when I have the game on Medium quality, the game seems to lag. Around every 10 seconds or so, my FPS will drop to about 12fps then go back up to 100. This is a brand new Mac Pro. 3.33 Ghz 6-Core 8GB 1333 MHz ATI Radeon HD 5870 When I had Windows on here it could run on Ultra with no issues. I do not see how OS X would make this unplayable even on Medium/Low. Do you have any ideas?