Get a wagon and put 4 critters on it
Walk wagon into a mine with a minedoor, the bigger the better and easier to test
Walk the wagon to the mine entrance but not outside the mine and then turn the wagon around and walk it to the back of the cave, this should bug your critters.
Observe that your critters are now no longer on your wagon, but above the mine. Watch RAM usage, it will go up the more you walk the wagon around.
Computers with low amounts of memory (4-8 gigs) will notice little lag; however, machines with large amounts of memory (in our case, we have 16 or 32 gigs) will begin to stutter very hard while someone is walking the wagon around.