Minecraft does fucky things with textures and polygons though. Like, half of the textures are algorithmically generated - that isn’t going to improve performance, but my point is it’s a totally different beast. It’s designed to be optimally simple from the ground up.
And Valheim’s models are hugely more complicated, from a behavioural standpoint. Collision detection with a cube is about as trivial as it gets, but when trees get polygonal, and you have heights that aren’t the multiple of the size of a block, and things can overlap, the whole modelling scenario becomes a nightmare - and games like Valheim have to model stuff that happens off-screen, too, like that bloody troll trashing your lumber base while you’re away.
Basically, Valheim is wayyy more complicated - and has a smaller team optimizing it - than Minecraft. The polygonal visual style is pretty superficial in the grand scheme of things.
It’s really hard to deliver a shoebox sized parcel through a proxy server.