fillRecursivePathList could load massive amounts of objects (ex:
all signatures below portal_synchronizations) even if no object was to
be removed. Instead, just iterate given lists (objects handled by
current instance, and actions to perform) and do as much rocessng before
actually attempt to load any object.

Sadly, the data structures available to this code induce an ugly O(n*m)
code, which may be optimised to O(m + log(n)) with more complex code if
really needed (but then, data structure should be improved, with a much
broader effect).