In changeset dc386436 Nikodemus made WITH-ALIEN rebind *ALIEN-STACK*
to itself. This made some work of SAVE-/RESTORE-DYNAMIC-STATE redundant
so far as the special binding takes care of releasing aliens.
He even pointed out that aliens were no longer freed one at a time,
but didn't remove the extra mechanism, which incidentally seems not to
have worked correctly, as otherwise the bug which prompted the rebinding
approach couldn't have occurred.
Net of all previous related changes, the minimal example
(lambda () (catch 'foo (funcall 'bar)) nil)
is 14 instructions shorter and 90 bytes less on x86-64.
Gabriel's CTAK benchmark runs 10% faster, maybe more.