You know what it's doing when it's running in scaled mode, right? It's rendering 2x the scaled resolution then scaling it down to fit native resolution. So for example, you're in "looks like 1680x1050" mode -- it's actually rendering 3360x2100 then scaling that to the native resolution of 2560x1600. I'm surprised that it gets the performance it does -- it's basically the same as FSAA 2x for the whole screen, all the time

(sorry for the late reply :) )