“Instant.page: Make Your Site’s Pages Instant in 1 Minute and Improve Your Conversion Rate Noticeably.”, Alexandre Dieulot2019-02-07 (JS)⁠:

Cheating latency

instant.page uses just-in-time preloading—it preloads a page right before a user clicks on it.

On desktop

Before a user clicks on a link, they hover their mouse over that link. When a user has hovered for 65 ms there is one chance out of two that they will click on that link, so instant.page starts preloading at this moment, leaving on average over 300 ms for the page to preload.

Another option is to load the pages when the user starts pressing their mouse without preloading. This makes for zero unused requests while still improving page loads by 80 ms on average.

You can also preload on hover or as soon as a link is visible and trigger the click when the user starts pressing their mouse, making your pages the fastest in the world.

On mobile

A user starts touching their display before releasing it, leaving on average 90 ms for the page to preload.

Another option is to preload links as soon as they’re visible.

It uses passive event listeners and requestIdleCallback so that your pages stay smooth. It respects data saver mode. It’s 1 kB and loads after everything else. And it’s free and open source (MIT license).