CakePHP users might want to listen to this suggestion from Tim Koschutzki on the Debuggable blog - he wants to help you save a half second on each request.

There are several ways to improve the performance of your CakePHP application. [...] Any performance improvement that does not effect how data is retrieved, stored and cached is welcome. If it affects your entire site and not only parts of it, it's all the better.

The performance boost comes in the form of an update to CakePHP's reverse route lookup functionality. Normally a lookup would have to be parsed and resolved back to their original location. They figured a bit faster way around it though - breaking the reverse routing feature for the sake of speed. The code for the hack is included in the post.