After just running Yahoo!'s YSlow tool in my browser on my personal website, I noticed – or rather, actually though about it for the first time! – that the results include my favicon icon. (Although this seems a bit like a sort of “department-of-the-obvious” type of question, please bear with me!)
Now there is a lot of literature on the web regarding website performance: reducing HTTP requests, creating and optimising dedicated domains to serve static files, combining text files and even images files (in the from of sprites). However, there is very little out there that looks into how popular web browsers handle favicon files.
I am not looking for actual details on caching/static file serving/etc. What I would really like to know is: How do the “big five” browsers – Chrome/Firefox/IE/Opera/Safari – deal with the downloading of favicons?
For example: Are they downloaded before or after page load? Do they induce a performance hit on page download times?