I'm finding that when I first go to a CiviCRM page in the morning there's a loading time of just over 1 minute(!)
There are no errors (on screen, nor in apache error log, nor in Drupal's watchdog) and after this delay everything works as normal.
Looking in firebug it's the actual page load that's stuck on client "waiting" for a full minute before it jumps to life and starts loading the zillion other requests typically needed on a CiviCRM page, which all go fast enough.
I've tried to trigger this. Clearing Drupal caches (
drush cc all) does not trigger it; clearing CiviCRM caches (via
civicrm/admin/setting/updateConfigBackend) do not trigger this delay.
However, adding a new user in Drupal does also trigger it. (Adding a new Contact in CiviCRM does not trigger it.)