Simulating airdrag and turbulence the compute-intensive way: simulating all of the air inside the pinball machine! You've got a few tens of liters of gaseous molecules to keep track of, should be enough to slow down most computers I would guess!
But I would be very surprised if any pinball software actually does that!
No one does it yet! Someone should import OpenFOAM into Unreal and make this happen. I want my pinball experience to require a dedicated server to help it.