Yeah booleans aren't great :/ better stick to CAD for that kind of stuff

What kinds of modifiers do you use? You said booleans right? It automatically makes it use the 'accurate' solver, which takes forever to calculate. So perhaps that's what it is, though I imagine you figured that much out already given you've used blender for years now.

Weird, I guess it's maybe trying to save each version of the model at every step of the modifier stack, so it doesn't need to calculate it every time you rearrange or delete something, just a guess though.

How old is 'new' in this case?

Regardless, it seems you would benefit from doing some retopo

Ah, so a big scene huh.

Did you maybe pack external resources into the blend file and forgot to clear the unused ones?

If not, no clue

Oh, so not the 'set material' node in GN, got it. Still more efficient in memory use and storage, since instead of a whole texture with 3 channels+alpha, it's only a vertex group

Do you use blender on steam? If so, updating the blend file to 4.3 might've done it

Damn, i didn't know you could do that! I'd usually just use an extra texture+mix shader node but this actually seems more efficient, thanks 🙏