Lua is a very powerful language and ideally suited for use with Lighttpd. While it will probably not supersede the traditional Web scripting languages (most of which begin with a "P"), its stable implementation, high-speed, and low-memory footprint makes it a great addition to our tool chest.

mod_magnet has the advantage of zero startup cost plus access to Lighttpd's stat cache implementation, at the price of stopping all other server tasks of this process while the scripts run. Therefore, it should be used only for very small tasks (like smart caching, picking a file or slapping a header and footer on a site). Also mod_magnet is probably the best tool out there for coding complex and dynamic rewrites.

For bigger tasks, Lua/FastCGI will have very little startup cost (compared to other Web scripting languages), while still giving us the whole power of Lua in a FastCGI environment. The added socket between Lua and Lighttpd costs little, performance-wise. And the low-memory footprint...