Clean out old revisions!
I know it has only been a couple weeks since PJGermain wrote his original post on this plugin but a lot of information disappears once it is no longer listed as "unanswered" or "popular". PJ's post should be bookmarked by everyone so that you can remember the plugin.
In PJ's post he recommends a WordPress plugin that you can install (and then delete) that will primarily remove old post and page revisions. It also has some other "cleaning" functions. The plugin is called "Optimize Database after Deleting Revisions" and can be checked out at:
Anyway, I have young sites but I am a packrat and a fiddler. I breed revisions like rabbits! I just ran this plugin on one of my sites and it deleted just under 200 past revision copies and decreased my load time by roughly 65%. That is huge.
Again, all thanks to PJ! Folks should bookmark his post and use this great tool!