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"It's great to have this stuff, but I don't think it belongs in core Python: I'd much rather that the core Python integer implementation remain simple, portable and low-maintenance, and work well for the domain it's intended for: small-to-medium size integers."
Yeah I agree. Maybe we need to explain that somewhere? In the devguide? Even in Python doc?
I know that they are super crazy^W fast algorithm to handle very large numbers (hum, what is large? more than 4096 bits?), but they are usually very complex.
Projects like GMP have ultra fast code with optimizations in assemblers. Having assembler implementation is clearly out of the scope of Python.
"Maybe I should change the issue then to "documentation missing": it nowhere says in the documentation that decimal has optimized multiprecision computations."
Well, nowhere means:
https://docs.python.org/dev/whatsnew/3.3.html#decimal
Usually, we don't document performances of a function, maybe only its complexity.
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You may move to the numpy community which is problably more keen on such optimization than the Python *core*.