I changed "High Detail Lots" to 3 on my system and reduced tree quality one step (this was huge for my heavily wooded shack) and that got it running smooth for me. When I moved my family to another town that helped the random stutters that I had been experiencing too since it trashed all my relationships (stupid celebrities with maxed charisma being friends with everyone they meet). I think I will opt-out of the celebrity system when the teenager I have been raising moves out.