TODO: Varnish this site
As you can undoubtedly tell from the HTTP response headers, this site is running on Plone. Plone's great for easy and speedy customisation (well, when you know your way around it!) but it's certainly not the quickest piece of software out of the box.
I've spent quite a long time with Squid in front of Zope 2 and Plone before, but to be honest new development on it seems to have stalled somewhat. Features that I'd really love to see - such as wildcard invalidation and Varnish, an HTTP accelerator. So hopefully I should get to see how well it works (particularly on the measly virtual server this site lives on!) and you should get a faster site response.
The architect's note is a particularly interesting read.
I'll report back when it's up and running.