LIB-29 (disc reading slow starting with libdiscid 0.3.0) affects also libmusicbrainz3, and with that all dependencies:
gnome-mplayer, goobox, kscd, libcddb4

I see that libmusicbrainz3 is not really maintained anymore (there is no maintenance branch and no version registered in the bug tracker),
but I want to report this anyways, because dependencies might complain.
Upgrading to libmusicbrainz5 would be better for the dependencies, using libdiscid directly is another option.

The patch itself wouldn't be a problem. I might add it here for reference when libdiscid 0.5.0 is released.