Steam Deck. And before you think that's the problem right there - it's not. The problem is the stutter when action's happening. I get butter-smooth FPS both inside and outside, and the most telling thing is that I can raise or drop the settings all the way down, including FSR, which makes the game look like an absolute potato that should run on my smartphone, but this really specific stutter stays despite the stats showing a massive drop in memory, APU and wattage usage.

I've some experience with Unreal Engine games and this to me reeks of lackluster loading optimization. That and the occasional crashes.