Firefox Page Speed Extension is a Gift From Google to Web Developers
The Page Speed extension is a valuable tool which can highlight the parts of your site that can be improved through better coding practices, smaller images or both. Google's developers recently released the source code for Page Speed, which is open source, so you can not only use the tool, you can see how it was created.
Page Speed evaluates each page's conformance to a number of different rules. According to Google, these rules are "general front-end best practices you can apply at any stage of web development", and of course Google provides documentation for each of the rules, which can be used with or without the Page Speed extension.
The tool is unique in that it evaluates the page's performance from the client's (visitor's) point of view, which Page Speed measures as the page's load time. Load time is measured as the time it takes for the page to completely load, and it starts when a user requests a new page and ends when the page is fully rendered by the browser.
This time is taken up by the browser as it resolves DNS names, initiates TCP connections, sends HTTP requests, downloads resources, fetches resources from the browser cache, parses and executes scripts, and renders objects on the page within the web browser. There's a lot going on behind the scenes!
Page Speed shows you how your pages complete these steps, and tells you what you can do, using its "best practices" to optimize your page's loading time. These best practices are grouped into five categories, as specified on the Web Performance Best Practices page:
- 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 overhead 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