external cache

Hey Folks;

I've been doing a lot of performance tweaking with some of the sites I run (specifically http://latam.kaspersky.com). We have been running Varnish for some time and I recently managed to convince the powers-that-be that APC is perfectly safe and we're nuts for not running it.

This is a question that had been asked before and discussed elsewhere. For instance, https://wiki.fourkitchens.com/display/PF/Modules+that+break+caching%2C+a... provides a list of modules that break the external and aggressive caching - some of them does not play well with normal cache either.

I need Drupal for Facebook and Organic Groups, both of which are listed as incompatible when external cache setting in the performance page is enabled.