Yes, this. Actually I first shared it here, because I thought that's cool and could work quite cleanly since mypy works well, but when I actually tried compiling one of my Advent of Code solutions with it, what i got was goto stuffed mess. I know I can't expect nice C code, but i certainly didn't expect gotos.

As for the performance gain - 13.5 s with Python, 9 s compiled. It was a naive implementation of AoC 2020/23, so a lot of array cutting, concatenation etc. So this isn't really math, rather lot of RAM I/O