Here’s a very good article on how to optimize performance and improve security on Apache Servers.

“This guide is written mostly for web administrators/developers, who want to optimize the speed and increase the security of Apache web server. Without a doubt, Apache is still one of the best web servers on the Internet. Being open source, loaded with modules that can do almost anything, Apache is a good solution for both development and production needs. This guide will help you get the best out of Apache web server by letting you control its usage with minimum resources.”

Link: Nasim Mansurov » Apache Performance and Security Guide