I promise you, UNO (Unattributed Navigation Overhead) is the best Christmas present you will get this year! UNO, not the card game, is the missing piece for many of your unsolved performance puzzles! UNO, not the organisation, even restores peace by keeping teams from pointing fingers and calling each other names when inexplicable things happen. […]

The readers of this calendar know that web performance is important. A faster site means happier users, better conversion rates, and, according to Google, higher SEO rankings. But how much does performance actually affect your SEO? It’s frustratingly unclear. While Google says Core Web Vitals are a ranking factor, they don’t say how much weight […]

Running web performance synthetic testing tools can really be a pain. It’s constant work to make sure to get stable metrics out of your setup so you can find those regressions. You use a bare metal server, you pin the CPU speed, you use a replay proxy to get rid of the noise from the […]

Speculative loading, or navigation speculation, is the concept of predicting (speculating about) which page a user might visit next and doing some or all of the work to load that page before they visit it. This way, if the user does end up navigating to the page, it appears to load much faster. Browsers have […]

In this post, let’s consider several optimization techniques for improving Core Web Vitals metrics for sites that are built with React. We are a team of speed consultants from the Czech Republic and in this article we would like to share some experiences from the many front-end performance optimizations we did for our clients. We […]

When looking at the Core Web Vitals, we often try optimizing each independently of the others, but that’s not how users experience the web. A user’s web experience is made up of many metrics, and it’s important to look at these metrics together for each experience. Real User Measurement (RUM) allows us to do that […]

Creating ownership for web performance metrics is challenging, especially if you want to ensure your entire organization is pushing along. Alex Russell has an excellent maturity model that captures this enduring journey (see infrequently.org blog). After navigating much of this journey over the past few years at Galaxus (www.galaxus.ch), I’d like to share one simple […]

Web performance metrics are essential for understanding and improving the user experience. While First Input Delay (FID) initially provided a positive outlook on interactivity, the shift to Interaction to Next Paint (INP) revealed significant areas needing improvement in responsiveness. However, the PerformanceEventTiming API, which is foundational for calculating metrics like INP, is not natively supported […]

Look, I’m just going to come out and say it: I’m a jealous man. I’m not proud of it, but I’m a jealous man. These past months and years, I’ve seen great update after amazing update (not you) being released for the Chrome Devtools Performance panel while my personal favourite panel, the network one, has […]

There are very interesting trends in performance engineering nowadays, so I’d like to share a few personal observations and thoughts (not representing in any way my current and former employers – and not pretending that it has any real research behind it). I spoke about Current Trends in Performance Engineering before, but here I want […]