songdogtech on "Too many MySQL connections and MySQL server has gone away"

@Kate: you've got plenty of RAM, and the CPU is not paging to disk, so that's good, so use mysqltuner.pl https://github.com/major/MySQLTuner-perl to configure the MySQL tuner.

Clean out your post/page revisions, too. I've seen databases drop to 10% of their original size with a resulting huge increase in performance. Use a plugin to delete revisions or run in phpmyadmin:

DELETE a,b,c
FROM wp_posts a
LEFT JOIN wp_term_relationships b ON (a.ID = b.object_id)
LEFT JOIN wp_postmeta c ON (a.ID = c.post_id)
WHERE a.post_type = 'revision'

@lulu said:

* Object cache (memcached)
* DB Cache reloaded

Object caching is php, not directly related to the database server. And a WP plugin that tries to do DB caching is not nearly as efficient as setting caching in my.cnf.