Huge perfomance issues on night races

I am having the same issue and I also have the same GPU. I have done some ''inspecting'' on what can be the issue, and it certainly can be the fog. Interestingly, during the F1 intros, before the camera gets to the F1 cars, game runs solid 60 fps. But when it gets to the cars and then it drops to 30-25 or less. But that's clearly a LOD thing... right?