Yahoo发布了一款基于FireFox的插件，名叫YSlow，这个插件可以分析网站的页面，并告诉你为了提高网站性能，如何基于某些规则而进行优化。Web标准辅助开发工具很多,但此款工具有着显明的特色与优点，我们往下看。

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages. YSlow is a Firefox 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.