I have seen the problem. I have either (1) rebuild site cache and/or (2) trashed preferences. It seems to help sometimes. Fonts do work into it sometimes, but I don't have that many installed. Library items, anchors, and sever side includes also cause the slow down i think. Check not to have any highlights in th epreferences; don't know but it might help.
Also, I have noticed that DW 3 takes about 15-25 seconds to quit. Has anyone else seen this? I am running a Sawtooth G4/450/256RAM.