Just FYI for anyone using KDE. This may or may not apply to openSUSE, but that's where I had the problem.
- Problem description: the kmix app/applet was eating about 50% (at least) of the CPU.
- Cause: A corrupted kmix profile
- Solution: Remove old kmix profiles with the following commands.
killall -9 kmix
rm -rf $(kde4-config --localprefix)/share/apps/kmix/
rm -f $(kde4-config --localprefix)/share/config/kmix*
Either reboot, log out/back in, or just run "kmix &" from the command line.