is there a way to resize the window? I would play it this way but the 1080p window is giant on my monitor.
try changing your desktop native resolution...I bumped mine to 1440p and windowed mode works now at 60 fps. It does render the steam overlay/fraps in 1440, so it's smaller etc. gtx 580 to panasonic plasma via hdmi.
Performance wise it seems to be a flawless 60 for me so far with everything at max. I did have to force traditional v-sync through inspector though, adaptive was giving me tearing from time to time.