Implementing 100% SEF URLs in Joomla! can be a little tricky so we've written a step-by-step guide that includes how to correctly configure your LAMP server.

There are some differences in implementing SEF URLs in Joomla! 1.0.* and 1.5, principally the requirement for third-party plugins.

We'll deal with the generic LAMP server configuration issues first and then deal with the [...]

UPDATE: The info in this post is deprecated. See the new post about eAccelerator instead.

I installed Turck MMCache PHP accelerator and I got a big improvement.

ApacheBench reported 4.52 pages per second before and 12.47 pages after installation (a Wordpress 1.5.2 page on a 1.2Ghz PIII). That a 275% increase in performance, with currently no observed problems. I tested this with both Apache2 and lighttpd, and got a similar boost with both.