Still, no answer to this yet. Despite the fact that the internet outside Reddit is hot with complaints
!I Still have issues with the game slowing down and sound glitching after 2 hours of gameplay
My system
AMD 5800X
Asus 3080ti Tuf
32 GIGs DDR4 Ram GSkill 3600mhz

Anno 1800 medium to high settings 1440p

First image shows memory usage in idle. just browsing on the internet

PC restart while playing AC Valhalla 

I’m 100 hours into the game. Works perfectly except for rare CTD I just restart the game and I can play for hours. 

BUT this latest update, twice has the entire PC restarted! Absolutely never happened before, anytime, ever. 

After 100 hours of gaming. I think I might have to reinstall the game.

Update
i reinstalled the game played three hours more, straight. Beautiful, butter smooth then, my computer restarts!