I've heard of JS packages that prefetch linked pages while the browser is idle.

Would there be any downside to doing something similar with lazily-loaded images?

At work, I'm on a fast connection. The Crutchfield home page loads very quickly, partly because below-the-fold images are lazy loaded.

But when I scroll down, even though I've been idle a few seconds, lazy-loaded images still "snap" into place. Not an ideal experience.

Shouldn't idle time be used to complete the page load?

Questions that come to mind:

1. How do I determine "idle"? requestIdleCallback, setTimeout(loadImages, 5000), etc.?
2. How do I performantly order the images to be eagerly loaded? Slowly expand the margin of an IntersectionObserver? (Is that even possible?)
3. How will this interact with the new loading attribute? Would I simply adopt the same strategy, just setting loading="eager" instead of changing the src attribute?

I'd love to know your thoughts, especially if you've implemented this - or explicitly chosen not to implement it for some reason.