Neville Hobson noticed this last week, and now after having spent a few days watching my Outlook 2007 install after installing SP2, I totally agree that it is running so much snappier than it ever has.
Back when I first tested Outlook 2007, I decided that there were a couple of things I didn’t like. One being the inconsistent use of the Ribbon UI, it’s on the individual email view, but not the inbox view. That remains, though I understand the next version of Office promises to move toward using the Ribbon UI everywhere in Outlook. The other issue was purely a matter of performance. Typically, it is simply very slow to open, slow to do a check for new mail, slow to close, and just generally slow.
Not any more. SP2, in my experience, has definitely brought back some of the speed that’s been missing. Got to love that!