put this command in the game's launch options:

taskset --cpu-list 0,1,2,3 %command%

What this does is a linux command that locks the game process to only the first 4 threads/2 cores.
This thread limitation seems to be enough to get the steam deck to increase the cpu speed on those threads and get decent performance vs the lagfest it was before.
The Decky command will get you more performance (apparently turning off SMT on Powertools will have the same effect as maxxing out your cpu frequency) but I respect those that don't want to install that stuff so here's the best I have for now after some research.
Thank you to the steam users on the thread that pointed out the SMT trick!

So again bear in mind performance won't be as good/consistent as with Decky/Powertools.
If anyone knows of a better command set please let me know.

Gentlemen, I am proud to announce a fix for the steam deck. The game does not load the cpu heavy enough to scale cpu frequency, so what you need to do is install decky, then powertools, and set a profile that locks the cpu frequency to 3500.
FPS goes from 20-30 to 50-60 with drops in cases of heavy gibbing.

Posters on a thread about poor performance have mentioned taking off the helmet (which turns off the hud) increases performance - perhaps a simplified hud option would help?
That and the low cpu utilization, I'm not really sure how to address that.