FastCGI is a language independent, scalable, open extension to CGI that provides high performance without the limitations of server specific APIs.

It can be used as web handler to serve RT with apache or another server that provides FastCGI support, but note that more help you'll find with apache as server. Read about alternatives and variants in the beginning of ManualApacheConfig.

If you decided to use FastCGI with RT then read ManualApacheConfig and FastCGIConfiguration pages, if you have not already.

Debian Packages for both Apache and Apache2: http://packages.debian.org/cgi-bin/search_packages.pl?keywords=fastcgi&searchon=names&subword=1&version=all&release=all

Project site: http://www.fastcgi.com/