I believe the reason why the game is so laggy for most computers is because the game renders everything in the map (NPC’s, entities, etc) consistently due to the fact that rendering based off perspective wouldn’t work out too well.
If they added rendering that worked based off what you see (and would then load in when others see it; for example, you are at water treatment and some guy goes to military tunnels and renders it for the server) you would have decent FPS but then when the server renders military tunnels, it would cause you to have a notable drop in consistent frames which would be annoying every time someone runs a monument.
If they managed to work out a rendering system that worked based off what you see ONLY, then the server would be too stressed out trying to piece together what should and shouldn’t be rendered and pretty much isn’t possible I believe.
To be honest, I’m not that familiar with how rendering works in Rust, but I’m assuming that the way they render it is just have everything constantly rendered which strains PC’s. The only way to optimize the game in my opinion is to lower the resource value that each texture has, to make it so that your PC is not strained on rendering high-value objects from farther away.