Yahoo also plays with website optimization tools?

YSlow is a Firefox add-on. After installation, it adds a panel to Firebug, reporting the performance score of a webpage's execution along with other relevant evaluations. It provides various information such as page load time and the components making up the webpage (scripts, images, Flash, etc.).

This tool might be YAHOO's response to GOOGLE’s website management tools, leading them to create their own website tool to compete directly against GOOGLE.