Written by When you profile a web page with Page Speed, it evaluates the page’s conformance to a number of different rules. These rules are general front-end best practices you can apply at any stage of web development. Google provides documentation of each of the rules, so whether or not you run the Page Speed tool, you can refer to these pages at any time.
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
Federico Cargnelutti 
Really a great information on google page speed and Web Performance Best Practices. Thanks for sharing.