A solution to stuttering and slowdowns that may work for some for full screen.
Disable Full Screen Optimisations
I found a solution trawling the steam forums for my stuttering and slow down issues in full screen a while back I thought I’d share here as it may help some as it did me.
Go to C:\Program Files (x86)\Steam\steamapps\common\RiMS or where-ever your steam folder is located and locate the exe and right click go to properties and click the compatibility tab and tick Disable full-screen optimisations.
It’s now smooth as a knife through butter for me now on full screen.
By Bandit