Re:macOS High Sierra: Anyone can login as “root” with empty ...
by leonroy on Wednesday November 29, 2017 @10:00AM
(#15807232)
Mavericks was a big one for extending battery life. It came quite a bit after Snow LeopRd and introduced timer coalescing which significantly improved battery life across the board for all MacBooks:
https://m.imore.com/mavericks-preview-timer-coalescing