The governor consists of goveror balls, sleeve, spring( inertial governor) and arms. It is conected to the Power output of the engine to regulate the speed over a period of cycles. Since governor these many parts and as they are attached to the output shaft, those (parts of governor) weight gets added to the shaft which may cause deflection of shaft or decrease in Power output (due to action of load).
If it decreases the powe routput, it will try to decrease the efficiency of the engine. Am I right ?....