Lighttpd is a secure, fast, compliant and very flexible web-server which has been optimized for high-performance environments. It has a very low memory footprint compared to other webservers and takes care of cpu-load. Its advanced feature-set make lighttpd the perfect webserver-software for every server that is suffering load problems. Installing lighttpd is quite simple under FreeBSD operating system using ports.
Popular sites using lighttpd as their primary server include the SourceForge developer community, the social media hub Reddit and the instant messaging service Meebo, while YouTube and Wikipedia use it to serve parts of their sites.
Read here how to set it up.