Today's updated bit of data is less scientific than the last time, but I ran the same tests one a few browsers again over the past few days, keeping every variable the same except for the browser in use: this time testing Zen, Arc, and Safari. This is the macOS Tahoe beta, so not a scientific test bench by any means, but the results after a 5 hour test run repeated twice for each browser was very consistent. In summary, after 5 hours of web browsing (M4 Pro MacBook Pro),

Safari brought the battery life down to 61%
Arc brought it down to 67%
Zen brought it down to 68%

Seriously, use the browser you like, don't worry about battery

This is good work from Matt Birchler. While the process isn't scientific, testing this breaks down some very wrong conceptions that have now become apocryphal. I also think that this really shouldn't be surprising. Chrome (and chromium) always did a LOT of optimization work that never really came through because Chrome was also shipping so much all the time. As a browser, chrome was always trying to do more than Safari. Personally, I feel like ARM made such a big difference for Chrome. All of those optimizations done for mobile are now likely compounding for the M-series of chips for Apple as well, making chromium based browsers really shine on the Apple platforms.

This is yet another reason why I really wish Apple would allow chromium based browsers on iOS/ iPad OS.