Thanks for the speedy and helpful response.

Keeping complexity down is fair. The wasted if-checks on subsequent iterations are certainly a negative trade-off. I saw that binarysort() is only called in one place, but I understand wanting to keep it generic.

I think that slow comparison functions, especially when repeatedly sorting short lists, are the main use case.

I don't know if that's common in performance-critical code. I've heard of using human choices for comparisons, when fewer decisions could provide a notable speedup. The patched code seems a bit slower in some situations, but is faster in others.

Do you think it's worth posting to python-ideas to see what people's use cases are?