In the continuing absence of anywhere to discuss these performance edge-cases (more below)... I've already mentioned recently that MyISAM is the enemy of Drupal performance. Because it requires a full-table lock, if you have lots of active members logged in at once, the process of posting a comment causes page rendering to cease entirely for several seconds. Onto today's point: The same table-level locking is *lethal* on a heavily- trafficked site which has both a) Content which alters regularly (like a busy forum), and b) Caching turned on. Try turning it off if your slow query log starts showing cache-related things taking 90 seconds (!) or more (!!). And then take a backup of your database and change these table types to InnoDB format. And then start looking at delayed inserts. jh PS: Still no bigsite/performance forum. Have we decided that Drupal doesn't *need* to scale? I missed that meeting.