[qxnqd]

Of course, if you are incompetent enough to write queries that use no indexes and you don't detect that before you push to prod, you will have problems there.

What I mean is: when you start optimising, no matter how well you do, you will eventually hit a CPU performance wall. Then you will realise that only a rewrite will get you out of that hole, and by then it will be late.

[acdha]

In my experience, many sites never hit that point of having CPU-bound Python code which they can’t afford; the ones which do hit that wall are usually large enough that they can carve out room for a C/Rust library, microservice, etc. rather than rewriting the entire thing.

[frankwiles]

I concur, I’ve worked on at least a dozen “web scale” Django sites and I can’t think of a single one where we were CPU bound.