Analyzing web pages performance with...

... YSlow, a Yahoo plugin for FireBug.

Yahoo has faced and battled many performance hurdles. Yahoo has organized there efforts into Yahoo's 13 Simple Rules for Speeding Up Your Web Site in an effort to help others tackle the same problems.

The list is compromised of the following...

• Make Fewer HTTP Requests
• Use a Content Delivery Network
• Add an Expires Header
• Gzip Components
• Put CSS at the Top
• Move Scripts to the Bottom
• Avoid CSS Expressions
• Make JavaScript and CSS External
• Reduce DNS Lookups
• Minify JavaScript
• Avoid Redirects
• Remove Duplicate Scripts
• Configure ETags

Yahoo has worked and developed a tool that analyzes and grades web sites based on these 13 rules. The tool gives feed back based on a A-F format.

If you wish to see a break down of how the scores are decided, Simone Chiaretta has a great post on Dissecting YSlow.