John, which version of McCLIM are you using on which platform? Give us the URL, etc.
I remember battling with mcclim.asd before I could release ASDF 3. It included a lot of cruft from the ASDF 1 days, and various bugs that I fixed together with rpgolman.
It is also possible that McCLIM or one of its dependencies has dependency bugs that used to be hidden by ASDF bugs: unlike ASDF3, ASDF1 and after it ASDF2 don't properly propagate timestamps transitively through dependencies. If somehow McCLIM has some kind of circularity or bootstrapping whereby a file that is depended upon earlier in the build is touched or re-created later in the build, or even more simply, a declared input that doesn't exist or a declared output that is never created, that will cause ASDF3 to reload a lot of things where earlier versions wouldn't.
Can you (1) check that you use the latest versions of McCLIM and its dependencies (2) find a minimal case where things go wrong, and give us a trace of perform-plan?
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org Ever wonder why the SAME PEOPLE make up ALL the conspiracy theories?