*load-fasl-or-lisp-file* determines whether
(load "foo") should load the binary file (
foo.xfasl etc, depending on platform) or
foo.lisp, when both exist. It may take the following values:
If the fasl is out-of-date, the lisp file is loaded, and a warning message is output in verbose mode.
Always choose fasl files in preference to lisp files, but when verbose, warn if the lisp file is newer.
Always choose lisp files in preference to fasl.
If the fasl file is out-of-date or there is none, compile and load the new fasl.
LispWorks User Guide and Reference Manual - 13 Feb 2015