I worked on an embedded system with an Allwinner chipset. We tried to reduce power consumption, not to save battery since it was a cabled system, but to reduce heat. It turns out nobody, not Allwinner who provided the BSP, not the board designer, nor the final customer who developed the application software cared to optimize the OS much. The CPU had four cores, but only one was occupied most of the time. But all cores were at 100% frequency. Configurable voltages were also all on the upper edge. I enabled frequency scaling, switched to the correct scheduler, and now the board was much cooler and ran with more than twice the performance.
I'm always surprized how many low-hanging fruit there are in these kind of systems.