The performance of a web site is one of the criteria used by Google and other search engines to determine the site's ranking. Various studies have shown that there is a link between performance and conversion rates. These are just two of many reasons to make performance optimization a mandatory step in your development process. However advice that was relevant a few years ago is often made obsolete by new browser versions or new technologies like HTTP/2. We will cover several aspects of optimizing a site from a performance perspective, debunk some myths, and also present tools that help analyzing a web site's performance.