My blog was getting slow so I called Dreamhost support. They wrote back
Okay, I see a pretty big issue. It looks like you’ve got 92MB of overhead (i.e. unoptimized queries) on your blog’s database. Optimizing the queries seems to have knocked your DB down to a more sensible 37.8MB – which can be trimmed further if you go thru and purge any questionable comments in Spam Karma as its tables take up 7.6MB. Go ahead and see how the optimizations have helped and let me know if you happen to have any further questions. I’ll be more than happy to help you get things sorted out if you need me to.
That helped muchly. I put on my calendar next to flipping my mattress, “Repair blog database tables to remove overhead. Then Optimize tables. Enjoy.”