Using YSlow to increase the front end performance of your web site.
published : 22.Aug.2007
YSlow is a Firefox browser add-on that works in conjunction with the Firebug web development tool, developed by Yahoo engineers it analyses your web pages and gives you advice on how small server configuration and web page layout changes can greatly increase your web sites performance.
After YSlow has analysed your web pages it gives you an overall performance grade, based on the 14 best practices for making web pages faster, as developed by Yahoo!'s Performance Team. You can watch a QuickTime Movie of a YSlow demonstration, before making a decision about installing the add-on.
Some of the rules are quite well known best practices, like ensuring your CSS is in the HEAD section of your HTML file, and that any JavaScript is at the bottom. However, some of the server configuration advice for adding expires headers to image and css files, and removing ETags was new to me, and it turns out that they are simple changes which are made to your .htaccess file.
Two small changes to your .htaccess that can increase your YSlow score.
Making these two small changes to my Apache server configuration via the .htaccess file, increased my YSlow score from a B (64) to an A (90) for the homepage of this site.
Adding Expires Headers to Image and CSS Files
ExpiresActive On
ExpiresByType text/css A2592000
ExpiresByType image/gif A2592000
ExpiresByType image/png A2592000
ExpiresByType image/jpg A2592000
ExpiresByType image/jpeg A2592000
Removing ETags
FileETag None
