Juli Clover, writing for MacRumors:
Without Low Power mode activated, an iPhone 6 Plus scored 1606 on the single-core processor test and 2891 on the multi-core processor test. When Low Power mode was turned on, the same iPhone 6 Plus scored 1019 on the single-core test and 1751 on the multi-core test, suggesting there’s a significant performance reduction when Low Power mode is enabled to save as much battery as possible.
Low Power mode can be turned on in Settings and is offered as an option when your device’s battery reaches 20% or 10%. When turned on, the battery indicator icon is yellow and Mail fetch, background app refresh, motion effects, and animated wallpapers are disabled.
I’m really excited about Low Power mode. As someone who has kept every iPhone I’ve ever purchased for two years, I can assure you that after about 16-18 months the battery life significantly drops. If this new feature makes the experience during those last 6-8 months a little more manageable, I’ll be more than happy with it.