I found this handy little gem a few weeks ago and it has made my Visual Studio experience even better ever since, especially when multi-tasking.  Turn off the 'Animate environment tools' option (which is on by default).

If you toggle the different tool panes on and off a lot like me then this will make VS (at least seem) much more responsive and less clunky.  I've done the same for similar Windows options (both in XP and Vista) to cut out some of the needless eye candy to get a little extra performance out of my geekbox.