The power saving feature in Android (I'm mainly familiar with Samsung phones so this might not apply to all brands) throttles the CPU in order to save battery. If the phone is being used for Web browsing, this results in slower page loading, which means that your screen is also consuming power for longer when in power saver. Does this mean in some cases the throttled CPU might actually result in higher battery consumption (specially taking into account that modern CPUs are pretty good at regulating their own power consumption)?
I'm sure the answer depends on a lot of variables so let's assume some specifics (although it would be great if one could make some extrapolations to more general scenarios):
- Samsung Galaxy J5 2016 phone (Quad-core 1.2 GHz Cortex-A53 CPU, 720x1280 Super AMOLED screen)
- Google Chrome browser
- Screen brightness is the same for power saver and non power saver scenario