Well most of the reviews I've read of RTM Vista code show that many applications are slower on Vista. There are some that are faster though. Most games are slower and those that use OpenGL are up to 1/4 the speed on Vista that they run on XP.

xp-vs-vista
Here is the conclusion page
http://www.tomshardware.com/2007/01/29/xp-vs-vista/page11.html


http://www.tgdaily.com/2007/01/30/bloggers_slam_vista/

Built-in Anti-Piracy / Anti-Copying algorithms at the kernel level.

Doesn't sound like my cup of tea and I like Windows eek

.