Caching headers are surprisingly complex and often misconfigured. Here we look at some key cache scenarios and recommend the ideal headers to set.

Exif data can be a privacy threat if you upload images on the internet. Here's how to remove it in the Linux command line.

According to httparchive.org images represent about 43% of the page weight for the median desktop and mobile page. There are many things to consider with images such as using the proper type, serving the appropriate image for the device and situation (srcset or picture), and lossless or loss

When starting on a web performance journey, many companies’ first step is to start monitoring performance metrics over time. But the second step is often much harder - now that you have all of this data, what do you do when you see a regression? How do you sift through the clues to connect a change in a graph to the code that engineers ship to production? How do you become a performance detective? In this session, Katie will crack open her casefiles to share some real-world examples where performance metrics changed for the worse, and walk through how to find the culprit. You’ll learn what clues to look for to understand a regression in your Core Web Vitals, how different performance metrics influence each other, and when to use data gathered from real users vs. synthetic tests in the lab.

To serve users at the global P75 of devices and networks, we can now afford ~150KiB of HTML/CSS/fonts and ~300-350KiB of JavaScript (gzipped). This is a slight upgrade on last year's budgets, thanks to device and network improvements. Meanwhile, web developers continue to send more script than is reasonable for 80+% of the world's users, widening the gap between the haves and the have-nots. This is an ethical crisis for frontend. Meanwhile, the most popular tools and frameworks remain in stubborn denial, but reality is not moved by ignoring it: when digital is the default, slow is exclusionary.

We got to a point where we had the lightest chatbox on the market, with a compressed size of 232KB (full load), where other chatbox providers would often load up to a megabyte. Discover How!

Why your analytics shows your site as faster than it is, and why FCP is a key metric to optimise for.

View this on WebPageTest.org...

An extension for Chrome Recorder to export a recorder session as a WebPageTest Custom Script

Use the transform and opacity CSS properties as much as possible, and avoid anything that triggers layout or painting.

Load non-critical resources when a user interacts with UI requiring it

A lot has changed since 2017 we I last estimated a global baseline for total page resource limits of 120-170KiB. Thanks to progress in networks and browsers (but not devices), the new baseline is much more generous: ~100KiB of HTML/CSS/fonts and ~300-350KiB of JS. But the devil's in the footnotes, and modern web development practices push the median page well above these guidelines.

La lettre de la DAJ Loi n° 2021-1755 du 23 décembre 2021 visant à renforcer la régulation environnementale du numérique par l'Autorité de régulation des communications électroniques, des postes et de la distribution de la presse (ARCEP)

GOV.UK dropped their jQuery dependency from their front end. You'll never guess what happened. (Yes, you will.)

First part of a series of blog posts that together make a coherent How-to guide on optimizing Drupal for speed.

The 512KB Club is an exclusive list of web pages weighing less than 512 kilobytes.

I've been thinking about social media images again. You know, the images that (can) show up when you share a link in places like Twitter, Facebook, or

Break HTML document size down by tag and attribute. Discover bloat like code duplication, large hydration state, and inline images.

How big are pages today vs. ten years ago? How does page bloat hurt your business? How does it affect Google's Core Web Vitals? What can you do to fight it?

Learn about how to optimize web fonts for Core Web Vitals.

Sometimes you want to share a Youtube video on your website, instead of just pasting a link. The prob...

Your may not think it, but your 404 page is an important part of your potential user journey. You should test its web performance as it can have a big impact...

HTTP cache headers can significantly improve the user experience of web applications. Understand their use and in what scenarios to employ them.

Social networks are everywhere online. Share, like and tweet buttons are popping up on a lot of webpages these days.The social buttons however have a big impact on the performance of a website. They load a ton of resources and slow down websites.In this post I'll tell you why I hate these social buttons so much. I'll also walk you through the ...

Gathering data about third-parties using free and open-source tooling

Data on third party entities and their impact on the web. - patrickhulce/third-party-web: Data on third party entities and their impact on the web.