EDIT: I had to take down my original response because everything you just said I just found why was happening when I installed bootcamp, the version you have is non functional, the shaders don't work, so everything except the characters look like ms-paint job, and it runs at half speed, I will say my apologies to you for having to go though with that.
Edit: the windows version is updated to a functional state, though, the speed issue still persist.