These rules are the key to speeding up your web pages. They've been tested on some of the most popular sites on the Internet and have successfully reduced the response times of those pages by 25-50%.
The key insight behind these best practices is the realization that only 10-20% of the total end-user response time is spent getting the HTML document to the browser. You need to focus on the other 80-90% if you want to make your pages noticeably faster. These rules are the best practices for optimizing the way servers and browsers handle that 80-90% of the user experience.
These pages are the companion web site for the book High Performance Web Sites. The examples referenced in the book are hosted here. Navigate through the rules listed below to find the associated examples. Each rule page also contains a link to the Yahoo! Developer Network Performance Blog. There you will find a brief summary of the rule along with comments.
- Rule 1 - Make Fewer HTTP Requests
- Rule 2 - Use a Content Delivery Network
- Rule 3 - Add an Expires Header
- Rule 4 - Gzip Components
- Rule 5 - Put Stylesheets at the Top
- Rule 6 - Put Scripts at the Bottom
- Rule 7 - Avoid CSS Expressions
- Rule 8 - Make JavaScript and CSS External
- Rule 9 - Reduce DNS Lookups
- Rule 10 - Minify JavaScript
- Rule 11 - Avoid Redirects
- Rule 12 - Remove Duplicate Scripts
- Rule 13 - Configure ETags
- Rule 14 - Make AJAX Cacheable
Read more:
- how these rules came about
- YSlow, Yahoo's performance analysis tool
- blog posts from YDN
- links from the book
sleep.cgisource code