So, what did I do?
- upped the installed memory from 512MB 533MHz to 2048 667Mhz – single biggest improvement!
- repaired and optimised all MySQL database tables for each site
- disabled all unnecessary wordpress plugins
- enabled WP-Super-Cache, a cacheing plugin to improve performance of popular pages, on all WordPress sites.
- resized and optimised for web all photos in the photo galleries
- installed the firefox add-on, YSlow, to my browser and used that to identify slow parts of the site.
- enabled the Apache2 module, mod_deflate, to compress elements of the page before serving them.
- tweaked mod_deflate like this:
<ifmodule mod_deflate.c> # compress content with type html, text, and xml AddOutputFilterByType DEFLATE text/html text/plain text/xml </ifmodule>