On the SitePoint PHP blog they've posted a tutorial from author Tonino Jankov sharing some techniques you can use to increase the performance of Apache and Nginx when serving up your web applications.

The article starts with some of the basics, introducing both the software and some of the concepts around their use and evaluation:

• an introduction to Apache and Nginx
• hardware considerations
• monitoring
• testing the systems (benchmarking)

It then starts on the tuning tips, one section for each of the web servers. For Apache it covers changes for the mpm modules, disabling htaccess and browser cache control with mod_expires. On the Nginx side, they mention changing the number of workers created, tuning the keepalive timout and setting up server-side caching.