It looks much closer to real human-written Asm than compiler output, which is itself a big win. No stupid calling conventions or obvious bloat. The unmistakably bloated inefficiency of "compiler slop" (that term wasn't used at the time, but those who lived through that Asm vs HLL era on the PC will know exactly what I'm talking about) is not present. I can always spot immediate optimisation opportunities with compiler output, but at a quick glance, not in this code.
...and now I have the idea of getting AI to decompile some existing binaries and then have it optimise/rewrite in the style of human-written Asm... run something like Windows XP or even 11 through it and see if it can be optimised down to a tiny fraction of its current resource usage.