Here is the page with a link to the sources (i haven't had time to had a look at it). Sorry, German page...
http://www.mikrocontroller.net/forum/read-2-195188.html
Have a look for mp3dec-test.tar.gz it seems to be for LPC2106 and as the author wrote, it consumes half of total performance.
Regards,
Martin
[Non-text portions of this message have been removed]