Stuttery, poor framerate on Galaxy S4

[MonkeyGrass]

Actually there is a much easier way to see if it's the charger/charging process, or some other system level proc that kicks in at low battery levels, and I'm going to try it later....

Keep the device fully charged and play with it plugged in. If it doesn't stutter, then something is going on in the kernel at low battery %. If it does, then it's something in the charging process itself that is causing the issue.