Every game it creates terrible framerate permanetly

I have found a issue that makes the game unplayable for me as every time I load into any game it drops to stuttery and terrible fps. Its not a specs issue as I was playing earlier and it was fine, and that was the only succesful play session I have had. Im not sure if its to do with the game not starting in fullscreen and a display issue but I need help because I do want to play the game.