Hello all, since my latest benchmark for PEP 580 [1] involved SageMath, which is quite a big project, I instead propose a much simpler benchmark involving mistune. mistune [2] is a Markdown parser implemented in the Python language. It optionally allows Cython compilation. It doesn't use any kind of optimization beyond that, but I created a branch [3] to use extension types instead of Python classes. Cython can either use built-in functions/methods or a custom class (which is not optimized but which would be optimized with PEP 580). I benchmarked mistune with custom classes [3] (binding=True, the default) and with built-in functions/methods [4] (binding=False). This is the median time of 5 runs: Binding=True: 9.063s Binding=False: 8.658s So this shows again that PEP 580 improves performance in actual real-world use cases. Jeroen. [1] https://mail.python.org/pipermail/python-dev/2018-July/154740.html [2] https://github.com/lepture/mistune [3] https://github.com/jdemeyer/mistune/tree/cython_pxd [4] https://github.com/jdemeyer/mistune/tree/cython_pxd_nobinding