Well, even though the engine is better, the server still has to do all the physics calculations. I don’t think there would be much of a difference in having to calculate dozens of coins falling with Havok physics and having to calculate dozens of coins falling with PhysX physics; the server strain would probably be about the same. I think UE4’s physics would be more resource-intensive given that it’s (apparently) more accurate, but this is completely baseless.
Mac already addressed this about pool anyway:
Given that you have to do all the calculations for all of the coin pushers, plus all of the players on the server, plus all of their pets, plus bowling (in the future), plus skee-ball (also in the future), etc., that’s a lot of load on the server.
It could be likely that they could just make a coin pusher using “fake” physics (basically just coding in how the coins should move without doing actual physics calculations), but I don’t think that would play too well.
Then again, they could just swap the coins out for something else (like capsules containing tickets), so there would be less things to calculate.