I have issue about fps while running PCars at the lowest setting, every single time I make contact with other cars, or even the race track barriers, the fps drop significantly from a stable 40fps down to 20fps. What's the problems with this game? I'm using a Dell Vostro 3450 i5-2450M, 8GB RAM with an external GPU MSI 750 Ti which I believe to be decent to run this game.