We're having a problem where the initial login to the Admin panel is really slow (usually times out). Most of the time it is fine, but after a long idle period the initial login to the Admin panel times out. Usually this happens to the first person of the day on the East coast.
I've deleted and disabled various plugins as well as reviewing the code to many of them (and fixing various issues). A number of them are in house, though I still have a few more to review.
I suspected it may have been related to WP cron, and cache GC (currently running Super Cache) or other scheduled jobs. On that hypothesis, I've disabled cron in wp-config.php, and am now calling it through crontab. This helped (the issue was worse previously), but has not completely solved the issue.
Today, I've turned MySQL's slow query log and will review it after we experience the issue. And I've also disabled all of the various feeds from the dashboard. Maybe tomorrow, I won't wake up to an email about the issue.
In the case that it doesn't work and the slow query log does not prove helpful, where else should I look?
I'd be interested in some pseudo-code or a high level outline of what happens when the user loads the dashboard. And also hooks that are commonly used/called at that time.
Filesystem is NFS mounted to the webservers.