WordPress announced a feature that interests me because it could improve performance, or rather perceived loading speed.
In version 6.8, scheduled for release on 15 April this year, speculative loading will be added. They announce that it can achieve near-instant page load times by loading URLs before the user navigates to them. This feature is based on the Speculation Rules API, a feature of the web platform that allows you to define rules about what types of URLs should be preloaded or preprocessed and how early speculative loading should occur.
According to its announcement post of 6 March, prior to implementation, the feature has been successfully tested on more than 50,000 WordPress sites via theSpeculative Loading plugin, which has now been moved to the Core with some modifications.
Based on data queried from the HTTP Archive and Chrome User Experience Report (CrUX) sets over the entire time since the plugin's launch, sites that enabled speculative loading improved their Largest Contentful Paint (LCP) pass rate by ~1.9% at the median, which, while it may seem like a small number, is a big boost for a single feature, considering that many sites with varying performance implications contribute to the data.
Although WordPress version 6.8-beta1 has been available since 4 March for testing, this feature has not yet been added to the Core.
Remember that to test Beta and RC versions of WordPress you can do it by installing them through WP-CLI, downloading the version to install it manually or on existing installations from the WordPress Beta Tester plugin, always on a test installation, never on a production site, and then choose the "Early Development" and "Beta/RC Only" channels.
At the moment, to test this speculative loading you have two options. One is with the plugin mentioned above(Speculative Loading) if you just want to test this feature, or by installing(Performance Lab) the WordPress performance team's development plugin that contains the complete collection of standalone performance modules. In both cases remember that, although some modules marked as "experimental" might work in production, it is advisable to test them in a test environment.
This is how the speculative load options are displayed.
Now it remains to be seen how it will behave alongside options that do, in part, something similar, although they are not exactly the same, such as Flying Pages, Wp Rocket's "link preloading", Perfmatters' Instant Page or LiteSpeed's Instant Click plugin.
What I understand is that, although similar in behaviour, since it is based on preloading links, it should be considered as an alternative add-on with which to get additional benefits by being able to pre-render pages instead of just preloading them. Prerendering allows pages to load truly instantaneously.
However, for instant loading to work, you must have the "pretty" permalinks activated.
Be that as it may, I have tested it on the fly and at first I haven't noticed a very evident change in navigation in my environment. It remains now to observe the behaviour over a longer period of time and how it relates to the cache and the rest of the site and do some comparative testing.
