Admittedly, I have a relatively speedy and capable computer, but I personally haven't had any slowdown issues with the 5.0.7 patch.
Might I suggest posting a dxdiag? Use the link in my sig if you're not sure how to do that.
But I'd guess, off the top of my pointy head, that it's something else running in the background that may have caused your issue. I'd recommend restarting your computer and seeing if that cures the problem. (I restarted mine before updating and, other than the usual "settling down" period that I have to go through after a reboot, I had no other issues.)
