Earlier this month, David’s heartfelt posting about leaving Mozilla made the front page of Hacker News. Traffic increased by 800% to his already-busy website, which slowed and eventually failed under the pressure. Request Metrics monitors performance and uptime for David’s blog, and our metrics tell an interesting story. Here’s what happened, why, and what you can do to prepare your site for traffic surges.

Web performance used to be easy. You’d time how long a page takes to load, easy. But the rise of client-side JavaScript has introduced bold new ways for websites to be frustratingly slow. Measuring this new slowness will take new metrics. Google calls them the Core Web Vitals. Each of the Core Web Vitals measures a different aspect of how a web application responds. This post will take a look at each of these metrics, what they measure, and how to use them.