Hi! its strange.. can you give me more information about your system spec? Thanks for the feedback!
Asus ROG X99 Strix Mobo, Intel i7-6800k CPU, 2 EVGA Gforce 1080Ti SC2, 32GB Corsair Vengeance DDR4 RAM, Windows 10 pro
It was running at about 11-15fps, but I have a feeling it tried to default to the fullscreen resolution at 4k, I've seen a few issues like this before.
You have to change the setup.ini file look for
under the line - aspectratio=0
(write the resolution that suits you)
Hope that helps..))