I’ve found the performance to be good. If you ever see slow client side performance there’s never an excuse for that in any language. JavaScript community are just bad programmers who add bloat to things unnecessarily. Anyone who’s actually benchmarked Python in the browser with real applications knows it’s impossible to see any actual difference in performance.
It’s never worth it to use anything other than Python. It’s just reached a point where even very complex problems are easy to “fix” in Python then “learn” in another language. I believe in 15 years all major companies will use it exclusively for web development.