In case you're interested how I found out about this: https://www.hahnjo.de/blog/2020/05/06/recursively-timeing-processes.html
before this change (commit 8fa5191cbf) /usr/bin/gsc called 18100 times, total of 2044s lilypond called 937 times, total of 1120s after an early version of this change: /usr/bin/gsc is obviously gone; lilypond is still called 937 times with a total of 1545s -> difference of 1619s https://codereview.appspot.com/548030043/
