Thanks, folks. I'm using the default 2010 theme, actually release 1.1 of the 2010 theme. Zero customization. Zero plugins (ok, I tried band removed supercache). Added one comment. Just about every page access -- including landing on the homepage -- is trying to grab 256MB on my 360MB VPS. Massive disk thrash. Not cool.
The whole point is, I have other things I need to do, and a turnkey CMS grinding a system out of the box is not in the plan.
If you've read the other thread, you know that I've done and verified all the usual PHP memory_limit stuff. I'm quite familiar with that. And although not mentioned in the other thread, I'm using WP_MEMORY_LIMIT in wp-config.php and -- surprise! -- even when I set this to a lower number to match the php.ini reported by phpinfo() I find in my server log that WP still tries to grab 256MB.
I had to stop using Drupal because it became such a PHP hog with only a few modules enabled. Someone suggested that I try WP because I was told it has a smaller memory footprint (at least for my simple needs), but that has not been my initial experience.
Is there perhaps a way to strip WP down to a minimal core which requires less peak memory? I still suspect that I have somehow malconfigured WP which is making it want so much memory. I'd be happy to report some metrics if I knew where to look. I'm open to learning that I've done something stupid.