Question - I had the opportunity to test out a few Retina MBPs at my local Apple store, and was surprised at how "laggy" and "jittery" the responsiveness was of Mission Control, spaces switching, and Safari window resizing. In comparison, the MBAs located right next to the rMPBs worked smoothly and fluidly, as you would expect. And this was with only a reasonably minimal set of programs open: Safari, Mail, iTunes, and iPhoto. This issue has been written about in a couple other threads on here. I wanted to ask, for those here who've ordered "ultimate" rMBPs, with the 2.6 or 2.7GHz processors and 16GB RAM, can you comment as to the responsiveness or "lagginess" of your MBP as I described above? The store demo units are 2.3 GHz/8GB, and I'm wondering whether it's just the base hardware that has a hard time keeping up with the software/graphics demands, or whether an ultimate unit would be comparably overwhelmed. While the display is indeed gorgeous - if the ultimate units exhibit the same performance lag on Day One out of the box as the base units do, I'd be disappointed with my purchase.