Are you running full screen by any chance? If so, try running it in the window and see if it experiences the same slow down.
Currently testing with a fresh install, no slow down since 30 mins in window (no full screen). I will post later about my further experiences. @Crewdawg: Thx!
Internet is ok on the Mac and it used to work flawlessly with the Windows XP installation that was there before. Maybe this is one of the reasons it is not working: it wasn't a clean install. And even with the new update, it is still not working. I do hope it is not an Airport issue either.
Have you tried both Shared and Bridged networking? After the update did the new tools install ok? Have you reinstalled them? Have you followed the steps on the knowledgebass article? http://kb.parallels.com/en/8978
Actually, I solved the problem by installing a brand new installation through Parallels auto installer. So apparently installing through my old XP disk wouldn't cut it. Thanks for all your help, guys.
I've also got problem with the "your pc will be ready in just a moment" screen. I got MacBook Pro 2011, any solutions?..