Learner2D + BalancingLearner too slow to use on many cores

I am trying to run 50 Learner2Ds inside of a BalacingLearner on 1500 cores.

The code is currently too slow to handle so many cores at once because the BalancingLearner requests too many points for the local process to handle, basically the notebook becomes completely unusable.

Whenever !34 (closed) is implemented we could probably write a large part of the Learner2D in cython to get a massive speedup.