I'll go out on a limb and say most of you know what a favicon is, but did you know that if you don't use one, Chrome and Firefox will still send a request? Even if you don't specify one in your header, the two major browsers (and probably also Safari) will time out looking for favicon.ico.

It's not a big performance issue by any means, but I thought this was an interesting find. When I was working on a little pastebin site, I actually made a 0 byte favicon.ico as it appears to be quicker to send that than letting the request time out.

touch favicon.ico