I've heard people say that it was comparable in speed to Windows XP, so that's good. I used the Alpha release (which was never officially released to the public, but was leaked all over torrent sites ages ago), it was quite speedy, looked pretty, and I had no problems running some older programs meant for XP.
Apparently, the public beta has slowed down quite a bit, but I never bothered to try it out. I hear from some people that its a resource hog like vista, but again, I have no personal experience with it. Supposedly, it is also coming with a Windows XP compatibility layer, which basically installs a copy of XP on your disk, and lets you use XP whenever you need to run some legacy software. This, however, seems like a giant resource whore. Maybe a step forward to eliminating some legacy code in Windows itself, but I'm sure they could have found some better way to emulate XP other than actually running the entire O/S in the background.
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