It doesn't matter how highly optimised it is, it is slop.
And DHH doesn't even know what he is doing. In this PR he now removed portability (and adding it back after he did the first pass of assembly and someone told him the mistake)
The end result in assembly isn't even faster than the Rust version also rolled in slop.
https://github.com/omacom/ttfx/pull/44
As they say, this is essentially polishing a turd and rolling it around in glitter, yet it still came from the gutter.