1-3 sec duration stuttering every 2 secs on an offline game

[nooberites]

I was playing prison architect and ran into a problem; the game would stutter incredibly frequently, but only when I had 20 workmen running around building stuff and when I had a sufficient quantity of my prison built. Even if I remove all of the workers but one, the stuttering is the same duration and frequency. It is also not a gradual change in frequency and duration for how much I build, it's more of a threshold that when is passed immediately starts to stutter rapidly. What's the problem?

Edit: After said threshold is passed, it is then a gradual increase in duration but not frequency, and actually seems to decrease in frequency slightly.