Running generator-sdl / generator-gtk on AMD64 (Gentoo Linux 64-bit), the music in the Sonic games sounds like it's running at about 40% normal speed and is quite "jumpy" (speeds up, slows down at random).
Is this a known issue? Is there anything I can do to help this situation?
I have not encountered this problem in any other games that I've tried.
Are you using the latest - generator-0.35-r3? i.e. ~x86 not x86?
If not ..as root:
echo "games-emulation/generator ~x86" >> /etc/portage/package.keywords
re-emerge, and try again. Otherwise, you might try using the sdlaudio use flag, because it defaults to OSS. Although SDL's audio handling adds latency that some find unacceptable.
Does your machine use AMD PowerNow! or similar which adjusts the CPU frequency to current load? This might cause some timing issues. You could look for lines with "nanosleep" in the code and comment them to see whether this helps.