Found this topic as well http://us.battle.net/d3/en/forum/topic/5573698171?page=3, for me it's basically random FPS drops when there's a few monsters on screen, before the patch it didn't drop that low, goes as low as 20 FPS sometimes :/.
Before the patch i didn't have any FPS drops at all, it went as low as 40 or so when there were a ton of explosions on the screen but that's about it, don't have issues on any other games, even updated the video driver recently just to be safe it wasn't that, the patch definitely triggered something in the wrong way for me :/.
For what it's worth my wife has a GTX 460 and is having the same problems. She went back to the previous driver and it helped a little, but her FPS readouts were well above 60 before the patch, and now frequently drop below --- http://i.imgur.com/oRbDb.jpg
You think so? Jeez, well, i hope it doesn't last long, either the next patch has to fix it or a newer driver then :/.
For what it's worth my wife has a GTX 460 and is having the same problems. She went back to the previous driver and it helped a little, but her FPS readouts were well above 60 before the patch, and now frequently drop below
Interesting, i can say the same, my FPS drops are worse after i installed the 301.42 driver, prior to 1.02 it worked flawlessly using 301.21 which i think was the driver before 301.42, now it doesn't work fine using either driver, lots of drops and in the Butcher boss which isn't hard-ware demanding AT ALL it runs like crap.