Can’t help but here is probably a good clue in your troubleshooting:
The GPU performance state APIs are used to get and set various performance levels on a per-GPU basis. P-States are GPU active/executing performance capability and power consumption states.
P-States range from P0 to P15, with P0 being the highest performance/power state, and P15 being the lowest performance/power state. Each P-State maps to a performance level. Not all P-States are available on a given system. The definition of each P-States are currently as follows:
P0/P1 - Maximum 3D performance P2/P3 - Balanced 3D performance-power P8 - Basic HD video playback P10 - DVD playback P12 - Minimum idle power consumption
You GPU is stuck in HD Video performance mode after you go on Battery mode. Good luck. Maybe check power settings in the system.