I have a long-running game, population over 800, ancillaries and buildings maxed out. Eventually I decided to use earthquakes and meteors to wipe out every single monster spawn. At this point monsters would only appear on the map if they spawned randomly, which seems to happen a couple of times per day. This was a small enough number to handle by manually throwing each monster in a cullis gate, but I wanted to go further. I noticed that monsters only spawn outside of your town's buildable area, so I destroyed all of my walls and most of my weapons and started building roads and fires to make the entire map buildable. Eventually monsters would only spawn from a single map tile. I built a fire next to that last tile, and within a few moments, the game crashed. With such a large population I was accustomed the game hanging periodically, so I waited several minutes, but the game didn't recover.
Here's a screenshot from when it crashed, you can see the roads covering the whole map:
and here's a screenshot of the game process:
This is a 6 core/12 thread processor so the CPU utilization corresponds exactly with one thread at full utilization (1/12 = 0.0833...). I realize you may not have been expecting a player to attempt this, perhaps I'm the first!