FastCGI is an improvement of CGI aimed at reducing the overhead previously described by allowing a binary to handle several queries. An AFS binary operating in a FastCGI mode can handle multiple queries at the same time using an internal multiplexing algorithm, and will keep on replying to queries until it is stopped or restarted.
FastCGI usually produces an enhanced user experience compared to CGI. It requires zero setup for AFS since this mode is automatically detected.
Used in conjunction with a fast lightweight web server such as Lighttpd, AFS v7 delivers fast replies to user queries, with a minimal latency.