[chongli]

The real killer with energy usage in browsers is idle wake ups per second. If you've got a lot of tabs open and they're all running timers, waking up, hitting the network, etc. then they're keeping the CPU from going into low power state and thus wasting a lot of energy.

Even though I'd prefer to use Firefox I tend to stick with Safari due to the battery life advantage which really shows when you open a lot of tabs.

[lloeki]

Indeed the most dramatic improvement I saw in battery life was when macOS and Safari started cooperating around timer coalescing using App Nap.