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Exceptional Performance

Exceptional Performance

Yahoo!'s Exceptional Performance team evangelizes best practices for improving web performance. They conduct research, build tools, write articles and blogs, and speak at conferences. Their best practices center around the rules for high performance web sites.

Best Practices

The Exceptional Performance team has identified a number of best practices for making web pages fast. The list includes 34 best practices divided into 7 categories.

Filter rules by category:
  • content
  • server
  • css
  • javascript
  • images
  • mobile
  • all
  1. Make Fewer HTTP Requests
  2. Use a Content Delivery Network
  3. Add an Expires or a Cache-Control Header
  4. Gzip Components
  5. Put Stylesheets at the Top
  6. Put Scripts at the Bottom
  7. Avoid CSS Expressions
  8. Make JavaScript and CSS External
  9. Reduce DNS Lookups
  10. Minify JavaScript and CSS
  11. Avoid Redirects
  12. Remove Duplicate Scripts
  13. Configure ETags
  14. Make Ajax Cacheable
  15. Flush the Buffer Early
  16. Use GET for AJAX Requests
  17. Post-load Components
  18. Preload Components
  19. Reduce the Number of DOM Elements
  20. Split Components Across Domains
  21. Minimize the Number of iframes
  22. No 404s
  23. Reduce Cookie Size
  24. Use Cookie-free Domains for Components
  25. Minimize DOM Access
  26. Develop Smart Event Handlers
  27. Choose <link> over @import
  28. Avoid Filters
  29. Optimize Images
  30. Optimize CSS Sprites
  31. Don't Scale Images in HTML
  32. Make favicon.ico Small and Cacheable
  33. Keep Components under 25K
  34. Pack Components into a Multipart Document

YSlow for Firebug YSlow icon

YSlow analyzes web pages and tells you why they're slow based on the best practices for high performance web sites. YSlow is a Firefox add-on integrated with the popular Firebug web development tool. This tool has helped improve the performance on over 50 Yahoo! properties by 25-50%. We're pleased to be able to share this with the development community so that others can join us in accelerating the user experience on the web!

Research

Research conducted by the Exceptional Performance team is documented in the following Yahoo! User Interface Blog articles.

Developer Support & Community

YSlow and performance topcis are discussed on the Exceptional Performance Group. Use this group if you have questions, issues, or need technical support.

You can also send feedback and report YSlow bugs and feature requests using the feedback form.

High Performance Videos

Along with the general web developments videos, you can also enjoy several performance-related videos now available on YUI Theater.

High-Performance Books by Yahoo!s

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