Originally Posted by till
Zend optimizer is not a real accelerator, it just optimizes a bit. I recommend that you install either eacceleretor or xcache beside zend optimizer.
Have you heard if there is one that works better than the other with ISPConfig and/or Drupal?
This is such a pain not being able to see in any log where this might be starting. I'm also going to check around the xen world to see if maybe it's something there I need to tweak.