There's no official word from Adesk, though in my discussions with the Factory, in my SR on the issue they came straight out and said it. 30% regression from 2008.

Others here who claim that 2009 is as fast as 08 -- I have trouble believing it. I've tested a lot of machines on this topic.

The latest beta build of 2010 seems to be as fast as 08, and perhaps the RTM version that's coming in a couple of weeks will be even faster...