This is exactly why its not moving anywhere. It should not cause system load. If it does, it means that something else is causing it. If I give an easy way out, I help those people, but do not fix the underlying problem.
It is something that is hard, as it won't allow me to pin down the actual problem! So far we've had multiple major issues that caused Cura to slow down when it started to slice. All of these caused everyone to point their finger at the auto slicing. All of these issues had -nothing- to do with the auto slicing. Correlation does not imply causation.
This is the reason why we don't change it, as the arguments that people have posed against it don't outweigh this. Recently there has been one argument that makes a pretty decent point, but I'm not quite sure if it's good enough reason to implement it.