What is your CPU? Overclocking it could help more than overclocking your GPU. I was having a problem with only getting around 15-20 FPS. Tweaked the setting and would maybe gain or lose a couple of FPS. I had to underclock my CPU, because of a shitty fan, and had thought I had put it back to normal. I just stopped underclocking it yesterday and now get around 35-40 FPS. I would look at the your CPU first.