I had been holding off on the new Retina MBP because of the UI lag....something that would just drive me nuts. As well as most apps were not retina ready. When it first came out I played with a floor model and the stuttering and lagging was very evident. Just went to the Apple store today and played with them again, but didn't notice any of the same UI lag that was there when these computers were first released. But I'm still reading things on here about lag existing. So is it fixed or isn't it? What update was it that seemed to make the most difference? More apps are retina ready now and I think if this lag is really fixed now I'll be ready to jump on board.