Frame rate drops to unplayable levels

After SH runs for a while let’s say a couple hours maybe the frame rates drop to an unplayable level due to very high CPU usage. This is usually fixed with a good game restart. Will update with more details when I come across the issue again, and will record gameplay until it happens if dev. asks me to.

Currently at 29 villagers
Specs: CPU: FX-6300/ RAM: 16gb/ GTX 760 2gb