Heh.
If anyone feels like applying themselves to further SQL optimisations, please submit resumes.
I asked istrata support about why we're so far behind in versions from the rest of the world. It's a Plesk (our control panel) issue. If I had SSH access from work, I'd not be so leery about breaking Plesk -- as it, it's the only way I can get in to do a lot of stuff, a lot of the time. Here's the support answer:
These packages were provided by RedHat in 7.3 which as you know is end of lifed. Updates that are available from the Fedora Legacy Project are security fixes only, no new versions of software will be introduced. That said you can safely upgrade MySQL to my knowledge (but do so at your own risk :-), but upgrading PHP, at least with the standard PHP RPMs will break Plesk. There is a guy on the Plesk Forums (Something like Atomic Monkey) that is building his own Plesk friendly RPMs but they are not supported so proceed cautiously if you decide to use them. The best solution I have is Plesk 7 which was recently released (you're running version 5). Plesk 7 includes an upgrade of PHP to 4.3.8 among many other enhancements (Application Vault, Spam Assassin, new skins, and lots of other cool features.). I can upgrade your Plesk installation to the latest version for $99.