Hi Darren,

I'm not a professional but may I suggest? There are a lot of suggestion to improve performance in the net is to use Nginx as a front-end server for static(images, javascripts, documents and etc) and Apache as a back-end server for PHP. This article as one example http://www.packtpub.com/article/configuring-apache-and-nginx May be it will help you.

Regards

Oleg