797... relax. Adjust your settings to minimum, turn everything off... and try again. If your performance improves, start turning things back on again one at a time. Once you find a good balance of detail and performance that you can live with, go with it. Also... remember that updates are never perfect, no matter what game you are playing. Developers can only take into account so many different types of systems and configurations when they are updating a game... there are bound to be a few bugs on their end that may need to be worked out as well... just be patient.
With that said... my update went fine, and I am running as good or better than I was before... so it's easy for me to say "be patient", when I can still play.
Seriously though... contact HTC and read the help forums for updates on fixes. Complaining here because your PC is having trouble running the new version isnt going to get you anywhere.
Good Luck