Beware- this may just be superstitious belief, but it seems to work for me as well as a few others, so I'll pass it along...
Anytime I get a new patch I end up with some stuttering problems. Not so much FR problems, but here's how I fix them. I go to the HTC folder, and delete my "cache" folder. I then go out of the game and do a disk clean-up and defragment (whether it says I need it or not), restart my computer, and restart my game. This seems to fix all of my problems, at least for a month or so. The cache folder rebuilds itself when you start the game again, so don't empty it out, just simply delete it. If I notice FR/stutter problems I repeat the process. I don't need to do it all that often, and it makes things run smoothly for me...