Somewhat related: I figured I was overdue for some maintenance, so I took the opportunity last night to install php 5.3 along with the IUS builds of APC and FPM, then swapped Apache for PHP-FPM. Right now, the forum feels a little snappier... page loads feel quicker, etc. Ram use is actually up a bit vs apache, but PHP-FPM is running out-of-the-box settings. I didn't have time to mess around with it beyond that.