[Question] Huge FPS loss!

[CaptRanger]

Today I have experienced a huge FPS loss. I went from ~60 FPS average on high settings to 20-30 FPS average. Most times it's completely unplayable. I've tried lowering every setting imaginable and still don't see any significant increase! Can anyone help troubleshoot what happened?

Quick system specs:
Windows 7 64bit
Intel Quad Core Q9300 2.50GHz
GeForce GTX 580 SC (latest drivers)
6 GB Ram
Soundblaster X-Fi Titanium HD
Corsair 750 W powersupply

 

[CaptRanger]

I should add that I put all my settings on LOW and still get less than 20 FPS on every map with microfreezes that make things unplayable! Surely I shouldn't get this poor of performance, should I? This wasn't a problem before yesterday.