Measuring page load and server response time was used for many years as the standard for our website performance, however, as we all know this is not a true indication of the user experience. As the time goes by, it becomes more and more clear that these metrics do not represent the actual user experience in the era of SPAs and PWAs. PSI (Perceptual Speed Index) is a metric that aims to solve this issue. In this talk, I will explain why is it important to measure PSI, the different approaches to measure it, how we do it at MyHeritage, and what we’ve learned.