I got a brand new Retina MacBook Pro (2.6 GHz Intel Core i7, 16 GB RAM, Mountain Lion 10.8.2) a couple months ago, and it was buttery smooth (for the most part) at first.
However, one day I turned it on and I suddenly got some terrible lag issues. For example, when I opened the Notification Center sidebar, it stuttered and chopped on the sliding animation. Similarly, the Genie effect stuttered when I minimized windows. The list just went on and on. At first I thought this was a hardware problem (it also turned out the screen had been mis-aligned), so I brought it to the Apple store. They couldn't find anything wrong with the graphics chip, but it they decided to replace my MacBook because of the bad screen alignment. I got the replacement yesterday. I restored my previous system from a Time Machine backup using the Migration Assistant. Everything was buttery smooth again, and I thought the problem was resolved.
However, this morning, I fired up my MacBook again and all of a sudden, the lag is back. The fact that the lag was nowhere to be found right after the Time Machine restore, but then suddenly back after a reboot is mystifying.
Can anybody please shed some light on this situation? Thanks!
UPDATE: I have tried turning off "Automatic graphics switching" in the "Energy Saver" system preferences, but to no avail.