The biggest power efficiency hack for macOS is to avoid running JS anywhere other than in Safari, and there as little as possible. Chrome and Firefox both eat b

The biggest power efficiency hack for macOS is to avoid running JS anywhere other than in Safari, and there as little as possible. Chrome and Firefox both eat battery like crazy. Firefox worse than Chrome, but either will take a couple hours off your battery life versus Safari. And running lots of heavy JS tabs or "apps" will do even worse. Not that that necessarily has anything to do with the differences you're seeing in particular, just worth noting. Wrong browser, 20-30% worse battery life. Wrong site open in some tab in the background, 30-60% worse battery life. The overwhelming majority of what takes my Mac battery life from 8+ hours to 4 or less is Javascript or some heavy Java IDE or something. User software that gives a damn about how much power it uses makes a huge difference, well outside of just "don't run video games on battery power" and other obvious stuff.