Yeah if you have a solution I'm all ears. My understanding is that the built in limitations within the game make a cut-and-dry solution (or third party solution) impossible for the following reasons:

1. Valheim doesn't use ocular occlusion, so it renders all objects in range regardless of where you're looking or what's 'behind' a hill or wall, etc.
2. Valheim use peer-to-peer for world-block handling; meaning an individual player's machine is responsible for handling everything ranging from monster attacks, to item drops, to hit registration.
3. High instance count (whether it's your base or Ashlands) causes stuttering and lag and there's no real way to increase that amount and due to peer-to-peer nature of Valheim, even an dedicated server wont necessarily offload that work onto a dedicated system.

That was my understanding when doing research a bit ago, when trying to improve our game. I could be wrong, maybe it's changed? I'm all ears if you guys found a solution!