The issue I'm having is that when ever I'm in Safari and running a video in full screen, for example a YouTube Flash video, the video gets really choppy. However, when ever I'm running the video in normal size, no problems. I have isolated this issue to a specific user account and specifically with Safari in this particular scenario. I do not encounter this issue on other user accounts. The user account that I'm using was migrated over from my old Mac. I'm thinking that some piece of garbage was migrated along with it and causing the issue. I have looked in Activity Monitor and did not see anything out of the ordinary and I have reset Safari but nothing helps. Though, nothing seems out of the ordinary in Activity Monitory, I have noticed that iStat is showing that the system is using CPU resources while videos are in full screen. In other user accounts, the system never uses CPU resources while running a Flash video in normal size or in full screen. I'm on a brand new 2011 27" BTO iMac with the CPU and GPU maxed out. So for this issue to be attributed to hardware is highly unlikely. I have been doing the full screen Flash video as a way to test out the capabilities of this machine and so far this has been the only hiccup. At this point, I know that it's a software issue. Any other thoughts?