I had come back after my computer had woken itself up from sleep overnight, and the memory was extremely high. The only thing loaded in the open project at that point was a scenery from a world with two players with no animation keyframes at that point.
This felt new, so if this is anomalous behavior, I'll gladly upload the project file in its current state (fully animated, but still seems to behave like this after some time).
This isn't the only time I had experienced this on the project. While working throughout the day, I'd restart Mine-imator as it'd climb from 500mb to 6gb over time.