It's only for Max because C4D already does this (mentioned in the release documentation) - Max was the only one of the two that still reparsed the entire scene when timeline scrubbing with IR enabled. C4D already only parsed what had changed. So the answer is to when it's coming for C4D is, it was already there :)
EDIT: Also remember that this is only the REPARSING, when moving between frames - the initial parsing still takes as long.