YSlow - Web site performance extension for Firefox

Posted on July 25, 2007, under Web Dev/Tech.

Yahoo! has made publically available their internal web site performance testing tool, YSlow. It’s pretty slick. YSlow will show you problem areas, and include information on how to fix them by linking to different parts of their “Thirteen Simple Rules for Speeding Up Your Web Site” document.

Here is YSlow’s summary feature list:

  • Performance report card
  • HTTP/HTML summary
  • List of components in the page
  • Tools including JSLint

Yahoo’s thirteen rules for speeding up your site are:

  1. Make Fewer HTTP Requests
  2. Use a Content Delivery Network
  3. Add an Expires Header
  4. Gzip Components
  5. Put CSS at the Top
  6. Move Scripts to the Bottom
  7. Avoid CSS Expressions
  8. Make JavaScript and CSS External
  9. Reduce DNS Lookups
  10. Minify JavaScript
  11. Avoid Redirects
  12. Remove Duplicate Scripts
  13. Configure ETags

YSlow depends on the Firebug extension being installed, but Firebug is such a great web dev tool you should have it installed already. ;)

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