I have a mid-2010 13" MBP (wrong year, wrong size) that's doing stuff that sounds like their listed symptoms. Not sure if it's just randomly going bad or if they haven't determined for certain that other models are affected as well.
Interestingly, the one change they did make in Xcode 6 was that the build progress bar at the top of the screen is now drawn in software - it used to be the only thing in the entire IDE that was GPU accelerated!