> There was demo that showed it normally takes ~100ms to click a mouse, and if you attach to the on-mouse-down, then by the time the mouse has been released (100ms later), you can have already fetched an updated rendered component from the server.

I think what you're describing is a form of preloading content but it's not limited to React.

For example:

The baseline is: You click a link, a 100ms round trip happens and you show the result when the data arrives.

In htmx, Hotwire or React you could execute the baseline as is and everyone notices the 100ms round trip latency.

In React you could fetch the content on either mouse-down or mouse-over so that by the time the user releases the mouse it insta-loads.

But what's stopping you from implementing the same workflow with htmx or Hotwire? htmx or Hotwire could implement a "prefetch" feature too. In fact htmx already has it with https://htmx.org/extensions/preload/. I haven't used it personally but it describes your scenario. The API looks friendly too, it's one of those things where it feels like zero effort to use it.

Hotwire looks like it's still fleshing out the APIs for that, it has https://turbo.hotwired.dev/handbook/drive#preload-links-into... for pre-loading entire pages. There's also https://turbo.hotwired.dev/reference/frames#eager-loaded-fra... and https://turbo.hotwired.dev/reference/frames#lazy-loaded-fram... which aren't quite the same thing but given there's functionality to load things on specific events it'll probably only be a matter of time before there's something for preloading tiny snippets of content in a general way.