Crealab

Web Performance in 2025.

Part 1: Predicting the future with Speculation Rules API

Welcome to the first part in our series of web performance articles in 2025!

Speed and performance are more important than ever for websites, users expect super-fast interactions and businesses that can meet or exceed these expectations will experience increased engagement, lower bounce rates, and, ultimately higher conversions rates.

As web technologies evolve, new innovations are reshaping our understanding of performance, user experience, and optimization. In this article, we look at one such upcoming innovation: the Speculation Rules Web API.

What is the Speculation Rules Web API?

In recent versions of Google Chrome and Edge, starting late 2024, a new web API, "Speculation Rules Web API" has been added. In simple terms it's a way to make the users next interaction faster, by trying to predict the users next interaction, and prepare future loading and execution, before it's even required.

The concept has long existed in operating systems, and even inside CPU-chips known as speculative execution. And it's now slowly finding its way into the web, as a new standards draft, currently only implemented in Google Chrome and Microsoft Edge.

How it’s used by Google Search

In Google search, Google has since February 2025 started experimenting with the technology, prefetching the html for the two first search results, and also following search-results if hovered by the user.

The goal being to as fast as possible show the search result website clicked on by the user. Saving valuable milliseconds of interaction and loading time. Significantly reducing the FCP (First Contentful Paint) and LCP (Largest Contentful Paint).

What does this mean for your website?

Opportunities, also known as "don't block the good intentions of the search engine" or "above-fold is king".

You could see it as in the future, when clicking a search result there might be no loading time for the initial html document.

That in itself is great! And a good initiative by Google that saves everyone's time.

In a perfect world where every website followed the web performance guidelines and made sure that the "above-fold" (what the user sees without doing the first scroll), initial page-view rendered fast without waiting for external resources or wasteful javascript, this would be true.

One could say, this development makes the optimization of the above-fold even more important than it already was. - If the loading of html is already done in the background, there is no excuse for being slow. If the website's initial html document can't display something useful to the user instantly, things are simply not done correctly, and good intentions are blocked.

This means really making sure that the initial html includes everything to display something to the user fast. Depending on the website, this might include making sure the first css is optimized or inlined, any slow javascript execution is removed, and that there should be no waiting for external resources.

It also shifts the focus of optimization from the initial load to any secondary images or other resources, since these might be the new things to wait for.

To take things further, the "Speculation Rules API", can also be used within your website, to make your own predictions for the Users next move. Significantly reducing the INP (Interaction to next paint) for any interaction that involves loading a new html-page.

Going forward and challenges

Currently, Google Chrome and Microsoft Edge are the only browsers that have implemented the "Speculation Rules API", but others might soon follow. Google and Microsoft solved the users-privacy concerns of the background-loading of unknown links, by using their own vpn-like proxies. So Apple (Safari) and Mozilla (Firefox) would have to use their respective VPN infrastructure to the same, which might delay things.

At Les Creatives we are following the development closely, and welcome Google's efforts. For many years we have built static websites with a strong focus on web performance and especially the initial page load. Our websites already don't block any good intentions for the above-fold, and we are currently looking into fine-tuning the INP performance where this new API can be a useful tool.

Always feel free to reach out to use for web performance questions.