Hi Alessio, thanks for that explanation (and sorry for my potentially ill-informed questions...).
So if the (compressed) FASL format is a Zip archive containing the class files, would it be worth compiling local functions to an in-memory Zip/JAR image along with the top-level forms' classes, and then COMPILE-FILE can write the whole JAR to disk as the FASL (and everyone else can discard it)? (This may be like what happens now; the Wiki page on FASL formats is a bit ambiguous, and I admit I haven't looked through the ABCL code yet.)
Anyway, on the strength of this brief discussion I can/should/will now go away and poke through the code. If/when I come up with anything interesting I shall report back to the list.
Cheers,
John :^P