underdriven

Underdriven describes something operating below its full capacity or optimal power level.

In audio and electronics, an underdriven amplifier or circuit receives insufficient input signal, resulting in weak or inadequate output.

The term extends to engines, motors, and mechanical systems running at less than their designed speed or force.

Figuratively, someone who is underdriven lacks motivation or isn't pushing themselves to their potential: The team seemed underdriven after losing their star player.