I have been playing for give or take a week on my new computer, and it played fine until this evening. Now I am very jumpy, and my FPS jumps all over the place, whether in-game VSYNC is enabled or not. No matter the settings, the issue is occurring, and it just randomly started this evening, even though no changes were made to my computer settings, or to the setting on D3, that is until after the issue started. Any help would be Appreciated

Amd 3.4 Quad 2X4 gigs ram. GTX 660