ORIGINAL: Deyrick Gibbins
It may be worth trying a lower graphic resolution, I dont know what graphic card you have or what resoulution you are using.
I know in most games that if you are pushing the limits graphically that sound is usually the first to suffer as the CPU cant cope with pushing all the data around.
I am running a Nvidia 6800 and getting frames rates at a minimum of 150-200 fps, so I don't think changing the resolution lower will be much use, but I will give it a try........just in case!
Andy