Actually what is happening when you restrict the flow on the output side of the pump is to increase the pressure, reduce the flow, and thus reduce the work that the pump has to supply. The reduced work load, i.e. moving water, results in a slight decrease in power consumption. Opposite to what may seem intuitive. These comments apply to centrifugal pumps only, which all pool pumps are as far as I know. I agree that in the long run the cheapest option is to replace the pump.
Al