How would you implement a benchmark then?

The kwargs thing is true… but I didn't design the API of pydantic. And it only happens on the small top level dictionary, not on all of them (unless it internally does it all the time).

Java has JIT, I agree that in that case keeping the output value is important. cpython isn't that smart. I honestly never tried to benchmark using pypy. I guess it could be interesting to try that.