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If you carefully read OP's response in the PR, he says he tried static typing make_list in addition to iterate_list. Your comment elides the resource allocation step.

Like OP, I observed that static typing make_list yields little benefit. It's runtime is 3x the runtime of iterate_list. And that makes sense. I'm not sure why we'd expect Cython to speed up the allocation of large numbers of Python objects.

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But OP didn't type iterate_list either. Perhaps he saw little benefit on one and assumed the same would happen in the other. Cython's annotation mode (cython -a) doesn't really help either here, showing both OPs and optimized versions with a strong yellow color, indicating that they would be about the same, but compiling and trying both definitely shows the improvement.

Another funny thing: making a pure python version that uses the sum() built-in results in code that runs 80% as fast as the cython version, but also gives lower error (e-8 versus e-4 error that gets accumulated when the numbers are summed up one by one).

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