The High Performance button in the in-game settings are for players with certain devices.
The following effects will occur turning on/off the High Performance button:
On: Higher frames per second, uses more battery.
Off: Limits your maximum Frames per second by half, uses less battery.
On: Higher frames per second, uses more battery.
Off: Limits your maximum Frames per second by half, uses less battery.
The High performance settings is turned ON by default.