Originally posted by Wridian:

What I wonder is if the devs somehow never noticed the problem themselves...

a) It's early access. b) a small team that, at the time of development, probably didn't have much resources to do lots of testing c) the huge player numbers after EA release introduced so many more variables - different hardware setups etc. So it exposed the problem. c) Unity is known to underperform when the game has some sort of landscaping. Give them time, they will fix it. Valheim two years ago used to look way different than it does now so this is just the beginning of the journey.