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Got Slow Web Pages? Find Out Why With YSlow

Firebug
Every wonder why your website loads slower than others? Wonder no more. Yahoo has released an excellent little add-on for the Firefox extension Firebug which analyzes a web page???s performance and offers optimization tips.

The extension, cleverly dubbed YSlow, adds another pane to the Firebug interface and offers up a bunch of easy to browse options including load times for each page element, both with empty and full caches, as well as various tips and additional options.

Obviously YSlow requires both Firefox and Firebug.

Yahoo has put up an FAQ about each of the tips, which range from the reasonably well know — put your Javascript includes at the bottom of the page — to the less practical option of using a content delivery network (which is generally very expensive).

Other suggestions offered by YSlow include:

  • Make Fewer HTTP Requests
  • Add an Expires Header
  • Gzip Components
  • Put CSS at the Top
  • Make JavaScript and CSS External
  • Reduce DNS Lookups

Although not directly related to performance optimization, there’s an option to view all styles in one screen, which can be a godsend if your page loads several different CSS files.

Naturally nothing is perfect and YSlow isn’t going to work on every page. For instance, it passes GMail with flying colors, but that’s largely because the initial page just loads some Javascript and little else.

Still for the average user looking to test and potentially optimize their site, YSlow is fantastic addition to the Firebug toolkit.

YSlow in action:

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[via Digg]