Have you ever wanted to know how your website measures in speed with regards to caching and actual downloaded files? If so then Yahoo has made available an excellent tool called YSlow which analyzes this information.

YSlow is actually an extension of the Firefox plugin, Firebug (an extension of an extension). Among other functions, it allows you to see how much data your pages will download with both a full and empty browser cache as well as offering tips to increase the performance of your site.

Overall, this is a fantastic tool for developers to help optimize speed and efficiency on your websites. There is a good overview of the tool on PHPied’s website, so give it a look if you are interested.