There's no way an AVX2 version of this would run as fast even taking throttling in to account. The throttling is aggressive in mixed code paths, but not really

There's no way an AVX2 version of this would run as fast even taking throttling in to account. The throttling is aggressive in mixed code paths, but not really all that bad if you're almost exclusively running vector code. AVX2 throttled a fair bit in the first implementation, and the penalty has generally reduced. I'd expect something similar here, it's just that Intel chips are barely changed in three years. And as the author says, 512 is a game changer, not just a wider AVX2. It's much more flexible.