In this post, I’ll discuss what I did at ALDO to measure the revenue impact of web performance without having to spend time making performance improvements.
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Back in October, rendering performance was something we had never focused on. Nobody was really talking about it, so there must be nothing there. It was only after we started measuring that we saw the potential.

Do you want your website to be fast and reliable? Don't use an EV certificate.

Varnish is definitely a way to go about Magento 2 full page cache in production mode. It is a lot faster than the default built-in option.

If I would need to implement image lazy-loading on a high-traffic e-commerce site today, I’d very likely go for a JS-based solution. Partly because the native solution only works in Chrome, but also because Chrome’s implementation is too eager and therefore not so effective.

A lot of performance issues stem from them simply not being very noticeable to those of us doing the building. Changing that wherever we can is one of the best ways to make sure that all that low-hanging fruit doesn’t go overlooked.

Si en réalité il est possible de décrire les choses correc­te­ment (bien entendu que c’est possible), alors insé­rer une formu­la­tion exagé­ré­ment large sert surtout à faire peur à l’em­ployé, à espé­rer qu’il se retien­dra plus que néces­saire, ou à pouvoir arbi­trai­re­ment lui repro­cher ce dont on jugera gênant après-coup.

This leads to a situation for users that’s almost worse than before. Instead of staring at a blank screen, now they get HTML lickety-split—excellent! But if they try to interact with what’s on screen, they’ll find that nothing is working yet. Even worse, once the JavaScript is delivered, and is being parsed, they probably can’t even scroll—their device is too busy interpreting all that JavaScript. Your users suffer.

A way of validating data independently of the programming language, a sort of mustache / handlebars, but only in the world of data validation.

The prefers-reduced-data media feature is used to detect if the user has a preference for being served alternate content that uses less data for the page to be rendered.

It’s become a trend for developers to reach for frameworks on every single project. Some people are of the mindset that separating HTML and JavaScript is obsolete, but this isn’t true. For a simple static website that doesn’t need much user interaction, it’s not worth the trouble. The more enthusiastic React fans might disagree with me here, but if all your JavaScript is doing is creating a non-interactive webpage, you shouldn’t be using JavaScript. JavaScript doesn’t load as fast as regular HTML, so if you’re not getting a significant developer experience or code reliability improvement, it’s doing more harm than good.

Comment réduire l’impact des visuels sur les performances de decitre.fr tout en gardant une bonne qualité d’affichage ? WebP, images à haut ratio et LQUIP !

For a recent New York Times article, I wanted to see if it was possible to create SVG charts that would work without JS.
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At the New York Times we're using a very similar technique to create JS-less maps tracking the coronavirus outbreak.