In case anyone cares (I suppose no one does), POIU, the parallel operator on independent units, that parallelizes compilation (but not loading) of ASDF component, with various options regarding determinism or non-determinism, is current bitrotten and not working on ASDF 3.3.2.2, and I disabled its functionality. I don't have the time or interest to fix it (I haven't been using CL at work for five years, and have stopped using it for new personal projects).
The other option I know to parallelize a CL build is bazelisp (the Lisp support for bazel.build), which I would bet is also bitrotten, since I haven't touched it in years, either. [An earlier option I worked on, XCVB, has bitrotten long ago.]
I am still available for advice in case someone wants to fix things — better ask before the information gets evicted to long-term storage.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org Superstition brings bad luck. — Saul Gorn