So I ran Skyrim through some benchmarks with surprising results (for me at least). For the test, I disabled crossfire due to issues with window mode not using the second GPU. Quality was set to max with no AA, 1650x1080 resolution... the reason being because there are a lot of mods running (I normally run 1920x1200), and I wanted a wide range of frame rates to make sure everything was in order. Also, ENB was disabled due to issues with FRAPS only recording at 30fps.
Disabling Aero
does increase performance, in both fullscreen and windowed modes. In my defence though of suspected lower performance in windowed mode, that's because of crossfire not working. Though I am kind of suspicious they all have 21fps as the minimum, was expecting at least some variation.
I'd eat my hat if I had one... but meh. So go disable Aero folks... what this has to do with Macs and Retina display I don't know, but that's where the conversation led.