Python is not slow. Your database and your blocking calls are.
The most common objection to Python — that it is slow — barely applies to a web backend, because the request spends almost all of its time waiting on the database, not running Python. A slow Python endpoint is slow for the same reasons a slow backend in any language is slow: N+1 queries, missing indexes, no caching, and synchronous external calls made one after another. We have inherited many Python apps blamed on the language, and the cause was the database every time. Fix the queries and the same endpoint moves from a 2-second p95 to under 200 milliseconds.