Before the stress test on 21st August I used the 301.42 drivers (I have GTX 460) and was getting about 60 FPS on max settings (with supersampling). When I saw a notice in the launcher, I decided to update to the latest beta drivers, and after that FPS varied between 20 and 45.
But on tonight's stress test it went all the way down to 15 and didn't get past 20 no matter what I did. And, honestly, it's unplayable.
I thought new drivers were supposed to optimise the game, not the other way around

Find content
Female

