For technical teams I advise to additionally track LCP(FE), or the Front End Component of LCP.

If nothing else, my hope is that this post helped shed some light on the fact that LCP is, by its very nature, a dynamic metric that is heavily dependent on user behavior. You can’t always know ahead of time what the LCP element is going to be for a given page, so it’s important that your optimization techniques can handle a range of possible outcomes, and adapt accordingly.

Le jeu de l'organisation de l’amélioration de l’accessibilité (OAA) vous guide dans la mise en accessibilité de votre service numérique.

Basé sur la dernière version du référentiel général d'amélioration de l'accessibilité (RGAA 4.1) vous pouvez :

• Faire un audit rapide (25 critères)
• Faire un audit complémentaire (50 critères)
• Faire un audit complet, dit de conformité (106 critères)
• Générer vos rapports d’audit et vos déclarations d’accessibilité

When measuring web performance, we often try to get a single number that we can trend over time. This may be the median page load time, hero image time, page speed score, or core web vitals score. But is it really that simple?

– Collect user errors
– Normalize & De-duplicate
– Cluster similar errors
– Measure User Impact
– Handle Script Error

When it comes to error handling, it truly is a team sport

Creating a performance story can only start with the data. Having a better understanding of your app’s state and continuously measuring and monitoring it is key to making sure you can ship the most impactful results to your users.

via Perf NL (https://calibreapp.com/newsletter)

Accessibility is a holistic practice that touches every aspect of creating a digital experience. This means it is also a backend web development consideration

via Perf NL (https://calibreapp.com/newsletter)

Finding out how browser and proxy caches behave (and misbehave)

You probably heard about the stories of Walmart that increased their conversion rate by 2% for every less second their page would take to load. While we found a clear correlation between page…

Progressive enhancement. Because sometimes your JavaScript just won’t work.

J’affirme ici que la non-qualité a des effets beaucoup plus graves sur la vie de ces populations. J’affirme que non, nous ne sommes pas égaux devant la non-qualité et que oui, si l’on se soucie vraiment de ces personnes, il est de notre devoir de proposer des contenus, des services, accessibles, sûrs, faciles à utiliser, simples, fiables, sobres et performants.

In this post, I want to look at ways to help mitigate and work around [the fact that site-speed is nondeterministic & most metrics are not atomic]. We’ll be looking mostly at the latter scenario, but the same principles will help us with the former. However, in a sentence:

🧞 Phenomenal Cosmic Powers, Itty Bitty Living Space

With both solutions measuring user experience metrics, it is natural to assume that they should be equivalent. It can be confusing when we see differences. This guide will explain why that can happen, and offers suggestions for what to do when the numbers do not align.

Priority Hints are a newly released browser feature, currently available in Chrome and Edge, that give web developers the option of signaling relative load-time priorities of significant page resources. These hints are declared by way of a new "fetchpriority" attribute in the page's HTML markup and are relatively easy to apply.

Early Hints is a recent addition to the HTTP Informational response (1xx) status codes. Information response codes are temporary status codes used to inform the client about the status of the request, while the server is processing the request to send the final response code (2xx-5xx).

Early Hints is specifically used to pass information on the resources that may be preloaded by the client. The client will eventually need these resources when it renders the final response from the server.

JavaScript, even if Cached, has significant cost on an end user's device; we'll discuss Disk, Parse, Compilation, IPC, and Bytecode Loading

CORS (Cross Origin Resource Sharing) enables web apps to securely access communicate across origins. But it comes with a performance penalty. In this tip, we'll discuss techniques for minimizing this penalty!