Think I've found the issue: your world has a lot of roads, which make it harder for the pathfinding to predict the cost of a certain path, slowing it down quite a lot.
I've uploaded version 1.3.1, which makes antelopes and skeletons ignore roads in pathfinding, optimizes it for people (by giving roads less priority), and optimizes the drawing code for roads. The save now runs just fine on my machine. Hope it will run better for you now as well.