Probably just worth mentioning that this blog is now running Movable Type 4.3, released yesterday. As well as a few new features, it apparently also boasts better performance, which is good.
One of the interesting new features is paginated search results, instructions for which are here. I may well check that out.
I upgraded as well. I’m on MT Pro 4.3 and noticed some odd Action Streams behavior (fixed now) with this upgrade. Also for whatever reason, the second and third columns on my index pages have mysteriously reversed themselves (still tracking that one down). But other than that, the upgrade was painless.