Greetings
We have just uploaded a performance update with around 4Gb of pre-built light maps allowing more hardware compatibility.
Be sure to have all your graphic drivers updated, about the framerate there is a cap actually so if the game runs smooth at 30-40 FPS it is working as intended for now, there are some areas where you could drop some frames but we will have this solved asap and also will look into a unbound framerate for upcoming updates.
Thanks a lot for your support and feedback, if anything please head into the discussion forums :)
Regards