hello, i just got my retina iMac with the M290X and a 4 GHz processor. I use it just for coding and scientific computation at work. In my two days of using it, I noticed that during half my sessions, there is incredible UI lag. For example, I dread switching to another app by swiping with 4 fingers on the trackpad because it'll take a good second and switch suddenly without any animation. Mission control etc have the same problem. The other half of my sessions seem much better and any lag doesn't get in the way of work. Does anyone know what makes the difference? Is there something i can do to stop this awful UI lag?