YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. YSlow is available for Firefox as an add-on integrated with the Firebug web development tool. YSlow grades web page based on one of three predefined ruleset or a user-defined ruleset. It offers suggestions for improving the page's performance, summarizes the page's components, displays statistics about the page, and provides tools for performance analysis, including Smush.it
™ and JSLint.
Visit the official YSlow website: http://yslow.org
YSlow is licensed under the New BSD License, with portions licensed by third parties under other license terms. To review the terms before installing, see http://wh.yslow.org/yslow-license
You must install Firebug: https://addons.mozilla.org/en-US/firefox/addon/1843