I tried all the YouTube video fixes and honestly, none of them did anything for me. They are all placebo.

The only thing that worked for me was a mod I downloaded to remove fog/mists from Valheim. I originally downloaded this mod because I found the mist in Mistlands to be way over the top and wanted to get rid of it. This mod had a huge side effect of drastically improving my FPS EVERYWHERE in the game.

https://valheim.thunderstore.io/package/Azumatt/MistBeGone/