I've been working through various optimization issues today and thought i'd share them with my future self and anyone else who reads this. mod_deflate I'd heard that getting apache to gzip your non-compressed data was a good idea and thought I was probably already doing that with my default apache2 setup on CentOS 4.4. What I learned was that: For apache2, the relevant module is mod_deflate (it used to be mod_gzip) My CentOS included the apache module by default, but didn't enable it. I did that according to the excellent documentation on the apache web site. I found a test site, which says that the html is now about 25% of what it was, saving me bandwidth and increasing the apparent response of my sites. wim leers I found a great article about drupal optimization here: improving drupal's page loading performance . He refers to a firefox plug-in developed by Yahoo that looks like a great tool, as well as a list of key issues to analyse for any site, and h...