Getting Started with Web Performance

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 ...

Cumulative Layout Shift (CLS), sometimes known as jank, is a measurement of how much elements move due to late-rendered content. You can think of it as a measurement of layout instability. It has become a common problem for many websites due to third-party scripts and tag management and its one o...

Largest Contentful Paint (LCP) is a measurement of how long the largest element on the page takes to render. It’s one of several Web Vital metrics that measure how real users perceive the performance of modern web applications. New measurements like Largest Contentful Paint are increasingly impor...

First Input Delay (FID) measures how long the browser took to respond to the first user input event. It’s one of several Web Vital metrics that measure how real users perceive the performance of modern web applications. New measurements like First Input Delay are increasingly important as JavaScr...

Web analytics is often based on invasively collecting and aggregating user data. But web analytics doesn’t have to be an invasion of privacy. A growing movement of businesses, including performance monitoring services like Request Metrics, are working to create sustainable web analytics tools. To...

News teams often compete to break the story first. We think they should also compete on being the first to load their website. Let’s apply our web performance skills to a real world example: which news website has the best performance?

Google has long used website performance as a ranking criteria for search results. Despite the importance of page experience for SEO, many sites still suffer unacceptable load times. Poor performance is often a confluence of factors: slow time to first byte, hundreds of resource requests, and w...

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 t...

I hate slow websites. They are annoying to use and frustrating to work on. But what does it mean to be “slow”? It used to be waiting for document load. Then waiting for page ready. But with so many asynchronous patterns in use today, how do we even define what “slow” is?