YSlow is a question with an answer: "Why slow?" This free Firefox extension can tell you why, and in great detail, when the question happens to be about Web page performance. YSlow tests and grades Web sites based on high-performance criteria established by Yahoo, and issues a report card describing areas for improvement. It also comes with a bag of tools for fixing some of the problems it uncovers.
YSlow is designed to integrate with Firebug, a suite of development tools bundled into a free Firefox extension, and YSlow's developer recommends installing Firebug first. YSlow placed a … Read more