Out of curiosity, I also ported the game to arm Linux with fex + upstreamed the wine patches in about a third the time and there's no FPS issues
(I am not joking. I did a port of an old utility, Dos Navigator, and I gave Claude+Codex a set of KPIs: cold start under 100ms, 30MB RAW image preview under 50ms, and a few others. I went to bed, and I woke up to a file manager written in Swift that is a joy to use, its so fast, esp. when previewing images. If I haven't requested it, it would likely be way slower).
Anyway, probably you are trying to run a 32-bit executable with Rosetta, that won't be fast, because Rosetta was never meant to run 32-bit things and has got a lot of pitfalls.
In my experience as game developer and porting C++ code tells such difference usually mean there are something really wrong with syncronization primitives. So 99.99% of the time code does nothing just waiting for something to unlock.
I recommend you try giving your AI an open ended task like, "it's at 4 fps even though it's a 22 year old game and the raw hardware performance is many orders of magnitude higher. Maybe due to running under Wine and Rosetta. Please figure out the simplest way you can unlock usable performance (30-60 FPS) short of decompiling, reverse engineering, and reimplementing the full game yourself natively. Maybe there is something else you can figure out for the performance unlock. The hardware is definitely there, so there has to be a way. The game is running so make sure you don't break it. Keep the same game behavior."
Regardless of which AI you're using, it will be able to figure something out in a few hours. 2004 pc's were 500-800 mhz, 128 MB RAM, and if they had a GPU at all it was 16-32 MB, 0.2-1 GLOP.
Your AI should be able to figure out a way to get it running in realtime.
If you want help, I've done some similar work, you could pop it up on a github repo or something. What is the game?
For me it's like they built a Ferrari with 4 thin bicycle tires. What a waste.