mp3's are compressed audio.. its the playback/uncompress thats munching your cpu.. an uncompressed mp3 of say 3/4mb will be 40mb in wave uncompressed form. not practical for storage.
an IFF probs would be huge too.
a MOD is a file containing samples, usually only a few hundred kb. a couple of mb at the most. Dont know the max file size on them.
