more scalable execute/update: avoid redundant traversal of invisible/finished nodes; tuned;
more scalable execute/update: avoid redundant traversal of invisible/finished nodes;
tuned;

MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle,MerelyAPseudonym/isabelle