in reply to
Perl v5.6.1 looking for .pmc files
Nick Ing-Simmons found an old, unused feature that was deeply burried into the perl code : when loading a module via use or require, perl checks whether there's a .pmc file along the .pm file, and newer; if it finds it, it gets loaded in place of the .pm. This was intended to be used by the byteloader, but apparently isn't used at all (unless something was missed.) Anyway it was too late to remove it.