Skyblock clearlag clearing minecarts

My problem is that I am trying to make a a master smelter system where a chest minecart is going across hoppers over furnaces. I want it to evenly split it but I can't do that as easily when minecarts get cleared. I can bypass it by emptying it and breaking it to a timer but if I don't have to do that it would be nice and if you guys are unable to do that can I at least know how often clear lag happens?