here are some ideas:
1) Maybe you can try to use as less as you can resources on your phone - uninstall all unnecessery app.
or
2) install some app for overclock to get more performance
or
3) uninstall HTC sense
or
4) install some other version of android (other named) which have better performance instead of fancy visualisation
5) 4) + 2)
I have same problem, but I am new user of android and I havent time right now.
notice: changing system you probably lose qurantee, but if you find way to turn it back... I don`t know