Earlier quoted context omitted.
Nice!. Is it intentionally slowed down? The reaction (for example when I click the checkbox) seem very slow in the demo page.
I was noticing this as well. I believe it's because each ui element must do a request to perform actions server-side (notice how the on_click handlers are python lambda functions). This is probably the main drawback; you need your server to be located physically close to where the UI is open or there will be a very noticable delay. It's probably pretty snappy when the server and browser are on the same machine, thoug…
I’ve tended to use this in UIs which rely on server state, and it usually makes things feel much snappier. In my experience it’s rare that an optimistic update isn’t fulfilled as expected, so the user experience is improved overall.
I’d hesitate to do it absolutely everywhere, though. In large forms it would be preferable to do batch updates rather than updating on every field interaction, for example.