I have a mid 2010 iMac with the 1gig ATI video card, quad core i5, and 4gig ram. The game runs extremely smoothly for most of the time except whenever the game tries to load something it or i zone into a new area of a new event or boss fight is triggered then my screen freezes and audio micro loops for about .5-3 seconds. I cannot play hardcore with this issue. I cannot isolate where the problem is as my FPS is consistently good, but my computer absolutely freezes at periodically. Anybody know where this issue might be coming from? How would i trouble shoot general performance eissues? I've already done everything on the Mac FPS threads, but id not feel like its a video issue.