Comment by magicalhippo

What I was getting at was that if you have a CPU bottleneck, reducing or removing that bottleneck can make your GPU work harder, which results in more frames per second but also more energy because GPU isn't idle as much.

This would be in contrast to say wasting a lot of cycles in a spin lock due to thread contention, where reducing or removing the contention might gain you both performance and lower energy cost due to less waste.