At the No Fluff Just Stuff (NFJS) conference I attended 2 weeks ago, somebody mentioned YSlow, which is a tool for analyzing websites in regards to performance and is a plugin for Firebug. Hence, this week I spent some time using it and fixing the issues YSlow found on my project.
It is really nice and almost addictive...YSlow grades the performance of your website in a number of categories. There is a good site at yahoo explaining those categories called: "Best Practices for Speeding Up Your Web Site".
That of course causes a lot of HTTP requests when loading the files and thus leads to a degradation of your website's performance.