Open-Source Archives - felix-arntz.me

Speculative Loading, or A Brief History of Landing a Performance Feature in WordPress Core

May 22, 2025

Two years ago today, on May 22, 2023, I opened an experimental pull request for a new module in the Performance Lab plugin. That little experiment was the very first step on a long road that ultimately led to the “Speculative Loading” feature landing in WordPress 6.8 last month (April 2025).

For those unfamiliar, the Speculative Loading feature enhances performance by speculatively loading pages a user is likely to visit next, which can make navigation feel almost instantaneous. If you want to dive into the technical nitty-gritty, I recommend checking out the “dev note” post on Make WordPress Core.

This post, however, isn’t about the what or how of the feature itself. Instead, I want to pull back the curtain and share the story behind the feature—the milestones, the discussions, and the collaborative effort that took it from a spark of an idea to a reality for millions of WordPress sites. The impact is considerable even for the entire web. Keep reading to the end for concrete numbers. 👇

Writing a WordPress plugin to generate image alt text with AI Services

October 23, 2024

In my initial post that announced the AI Services plugin for WordPress I mentioned several times how it simplifies using AI in WordPress by providing AI service abstractions as central infrastructure.

In this post, let’s take a more hands-on look how you as a developer can use the AI Services plugin: We will write a WordPress plugin that generates alternative text for images in the block editor – a crucial aspect of good accessibility, which AI can be quite helpful with. Since the feature will be built on top of the AI Services plugin, it will work with Anthropic, Google, OpenAI – or any other AI service that you may want to use. And the entire plugin will consist of less than 200 lines of code – most of which will in fact be for the plugin’s UI.

Introducing the AI Services plugin for WordPress

October 9, 2024

It’s safe to say the topic of generative AI doesn’t need an introduction in today’s age. It has been emerging throughout the tech world. However its adoption in the WordPress ecosystem has been slower than in other ecosystems. This is for various, mostly technical reasons that make implementing generative AI features in WordPress harder than elsewhere.

That’s what I’m trying to address with AI Services, a new free open-source plugin that is now available for early access on GitHub, and as an early version 0.1.0 in the WordPress plugin directory.

AI Services is an infrastructure plugin which makes AI centrally available in WordPress, whether via PHP, REST API, JavaScript, or WP-CLI – for any provider. Other plugins can make use of the APIs from the AI Services plugin to easily add AI capabilities to their own plugins, for whichever third party service they prefer: Whether it’s Anthropic, Google, or OpenAI, whether you’d like to use another service, or whether you’d like to leave the choice up to the end users of your plugin – AI Services makes it possible by providing access to the various APIs in a uniform way. It acts as a central hub for integrating AI services, allowing plugin developers to focus on functionality instead of managing individual service integrations. As an end user of WordPress, that means you have more control on how you would like to use the AI capabilities provided by the plugins.

My WordPress Core Contribution Workflow

September 22, 2024

During an informal meetup between the WordPress Core committers attending WordCamp US 2024, one of the topics we discussed was how each of us was handling commits. Given that WordPress Core uses svn and Trac for its source of truth but git and GitHub are encouraged for contributing, it can be a bit of a hassle to synchronize changes when it comes to committing code to WordPress Core.

Fortunately, this is only relevant for the folks that commit code, i.e. nothing that a new contributor needs to worry about. Yet, there’s a good number of committers, and new ones are added regularly, so we thought it would be good to document our workflows. There’s no “official” documentation about this, simply because there’s no universally recommended approach. Many committers have come up with their own solutions throughout the years, so we decided it would be a great idea if each committer documented their approach, so that we would have a number of solutions to compare and for newer committers to review and choose from.

This brief article outlines my personal workflow for committing to WordPress Core.

Measuring website performance using WebPageTest (with WordPress 6.2)

April 6, 2023

In my post from last month, I am sharing my experience from rebuilding my WordPress website using a block theme, including a performance comparison. As part of that post, I included a spreadsheet with a detailed performance breakdown from before and after the changes. I only provided a bit of context for how I conducted the performance comparison in that post, however as promised, in this post I am sharing the concrete methodology that I used and how you can use it to measure performance of websites yourself.

In order to better explain the methodology, I thought I might just do another similar kind of analysis that I would go over in this post. Last week, WordPress 6.2 was released, so no better opportunity than to measure how updating my website from WordPress 6.1 to 6.2 affects its performance!

I created a spreadsheet with the full data for this new analysis, and in this post we’ll go over the process for how I got that data in detail.

Rebuilding my website using a block theme

March 6, 2023

It’s been a while since I have posted on my blog. In fact almost 2 years now. But it’s been even longer since I have significantly touched the foundation of my website; other than the regular updates, adding a small plugin here or there, my website had been using the same infrastructure and theme since 2019. A lot of it even already existed the same way in 2018. My website had gotten really out of date, in terms of both content and technology. Some of the blocks I had implemented years ago were no longer working, so part of me was even afraid to open the block editor.

A few weeks ago, I finally decided to change that and modernize my website. But it didn’t just came out of nowhere. Specifically, I wanted to update my website to use a block theme. I had been excited about them since they were in the exploration stage already in 2019, pretty much as far back as when I was rebuilding my website, “the old way”. The opportunities for enhancing performance due to the new block theme paradigm seemed extremely promising to me.

Now that we’ve already had 3 major WordPress releases to establish and refine the new infrastructure, I decided to really give it a try. In this post I’ll share my experiences with you as well as the outcome and how it is impacting performance.

Exploring Sitewide Gutenberg Usage Today

July 10, 2019

Phase 2 of Gutenberg is all about taking the compelling capabilities of the block editor to the site level. WordPress 5.0 introduced it as the new editor for post content, but that was only the beginning. Blocks are a powerful tool and inspired by the learnings of various other formats of editing that WordPress and other platforms have been using over the years, so it makes sense for them to provide a unified approach to reusable content. The difference between shortcodes and widgets for example has pretty much been non-existent, and it felt weird to create a certain UI component only for one of the two, or having to write some duplicate code to address both layers. With Gutenberg being expanded to become the editor for your entire WordPress site, beyond the post content bubble, this problem will be solved. Furthermore, it will bring the new editor much closer to being able to fully compete with existing layout builders.

Each of the steps to get there (e.g. migrating widgets, menus, and possibly even other elements fully controlled by the theme today) poses several challenges, so it might still be some time until we get to experience all this functionality in its proper implementation. Therefore, inspired by a conversation with Morten at WordCamp Europe a few weeks ago, I wrote a tiny experimental plugin that allows you to use blocks on a sitewide level and explore what the theming of tomorrow could look like already today.

Vier

June 29, 2019

Last weekend I participated in WordCamp Europe 2019, my fifth one of these annual events for the European (and beyond!) WordPress communities to meet, exchange knowledge and celebrate themselves. This fifth WordCamp Europe also marks my fourth anniversary as part of the WordPress community, as the 2015 event in Sevilla was my very first interaction with the community. Hence, it is time for my annual personal recap of what has happened in the past 12 months.

Tres

June 24, 2018

I have a relatively good memory for dates, so I noticed that it was exactly today three years ago that I joined the WordPress community. While I have drastically failed in blogging more over the past year (and I guess I intend to continue that “streak”), I thought it would be a good time for a recap of what happened in the past year since I wrote my last such recap.

Thoughts on Gutenberg

July 9, 2017

Several people have already posted their thoughts and impressions about the new Gutenberg editor for WordPress, to highlight pros, cons and everything in between. Here is my perspective on it.

Category: Open-Source