PreventEndCrystalLagMachine - dniym/IllegalStack GitHub Wiki
ON BY DEFAULT - Affects ALL Versions with End Crystals/Armor Stands/Minecarts/Pistons
Prevents pistons pushing / pulling of non living entities into each other, once lots of these entities are crammed together it generates a lot of lag.
To enable / disable this protection use the following command: /istack toggle PreventEndCrystalLagMachine
This protection has no extra options.