In benchmarks slower in Python 3.7 compared to 2.7 at https://speed.python.org/comparison/ I found pickle_pure_python and unpickle_pure_python. These benchmarks test the pure Python implementation of the pickle protocol.
I don't see the point of testing the pure Python implementation, since the C accelerator (_pickle) is always used by default in Python 3. I propose to remove this benchmark. What do you think?