I played around with the godbolt he put up, I honestly found that adding __restrict to the pointers appears to make the biggest generated code difference and th

I played around with the godbolt he put up, I honestly found that adding __restrict to the pointers appears to make the biggest generated code difference and the code seems to be written with that in mind. That does ruin portability sadly, but it does cut the number of instructions generated down significantly and allows the compiler to use memcpy. I'd be curious to compare that to his normal version in a benchmark