Check it out:
Beyond the plugin itself, the rules are definitely of interest:
About the performance best practices
Page Speed evaluates performance from the client point of view, typically measured as the page load time. This is the lapsed time between the moment a user requests a new page and the moment the page is fully rendered by the browser. The best practices cover many of the steps involved in page load time, including resolving DNS names, setting up TCP connections, transmitting HTTP requests, downloading resources, fetching resources from cache, parsing and executing scripts, and rendering objects on the page. Essentially Page Speed evaluates how well your pages either eliminate these steps altogether, parallelize them, and shorten the time they take to complete. The best practices are grouped into five categories that cover different aspects of page load optimization:
- Optimizing caching — keeping your application’s data and logic off the network altogether
- Minimizing round-trip times — reducing the number of serial request-response cycles
- Minimizing request size — reducing upload size
- Minimizing payload size — reducing the size of responses, downloads, and cached pages
- Optimizing browser rendering — improving the browser’s layout of a page
At first blush it’s not yet the resource that YSlow is, but it’s a great complement to the Yahoo! tool. The report in inefficient CSS selectors alone is worth the download.