At the moment, IncrementalScoreCalculator does not have the following methods:

beforeProblemFactAdded/after...
beforeProblemFactRemoved/after...
beforeProblemPropertyRemoved/after...

Instead, the IncrementalScoreDirector calls resetWorkingSolution(...), which is inefficient.
Unfortunately, we can not fix this in 8.x, as we can not add new methods to the interface - even of they had default implementations, we can not have these implementations call resetWorkingSolution(...), as we do not have access to the working solution.

Therefore this goes on the backlog for 9.0.