Actual bottleneck in examples is sqlalchemy, like 10x overhead easily. I find it quite funny. There is no real difference in web frameworks for real apps in terms of overhead.
However, my experience is that this isn’t always the case. My company has a medium-large Python web app in production, and having viewed performance profiles, I can say definitively that Python code execution occupies a non-trivial amount of processing time. Of course the single largest time sink is the LLM requests we make, but if we could magically nullify the Python processing time, our latency would significantly improve.
The culprit in this case may be specific to FastAPI and Pydantic rather than Python generally, but the point still holds that not all web frameworks and resultant apps are equivalent.
That said, I’ve been dreaming of rewriting large chunks of it in golang. I’ve always known Python was relatively slower than other languages, but I saw a recent benchmark measuring golang as 50x faster than Python. Perhaps the benchmark won’t translate to real world performance, but still - 50x is difficult to ignore.