Maybe it's log problem (Score 1)

I do not have the same problems with Windows 7. I have an interesting distinction though: I rarely reboot my system. I work at home, on desktop computer, and it usually runs 24/7. So maybe, just maybe, with every reboot something grows (registry or some logfile, I don't know), which causes system to slow down. Also, I'm always switched to "windows classic" UI theme, because it works fast and I don't really need transparent windows, shadows, and other shitty effects.