If you've managed to get battery life from Linux and Firefox even remotely near default fresh install of MacOS and Safari, you should write that up and post the link to it on HN.
Then again, Windows was even worse. It was constantly waking itself up in a cramped bag, where it would try to forcibly install updates, overheat, drain the entire battery, then shut down and need to charge for 30 minutes just to light up at all. At which point it would boot into the recovery menu since it botched an update and needed to try again.