Overall drop in performance (FPS) for no apparent reason

I was running the game since launch, perfectly fine on medium settings getting on average 30 fps (sometimes higher). I log in the next day, and out of no where I am now getting between 10-15 fps, even when I lower my settings to the lowest possible.

I made no changes to my computer, and even tried installing the latest gfx card drivers to no avail. I can't understand why this sudden drop in performance would happen, but it means I can no longer player until it is resolved. If I cannot resolve it in a few days, I will have no choice but to quit playing.