Nice GUI (opens in new tab)

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, though.

Nope, it's doing a round-trip to the server on each interaction. You can inspect the websocket and see the messages. The notifications are generated by a Python function running on the server, there's no client-side logic.

Oh yeah that makes sense Material design is both ugly and dorky to use.