There is absolutely no requirement or indication that Python UI framework will have to follow the same principles as JS ones. > your site's loading time won't

There is absolutely no requirement or indication that Python UI framework will have to follow the same principles as JS ones. > your site's loading time won't impress users. Anybody who used client-server apps in the 80s and 90s is not impressed by browser-based apps either. Those expectations can be managed in so many ways.