Firefox macOS test build is far better for your battery life
Firefox on macOS will soon be more beneficial to MacBook Air and MacBook Pro users who want to preserve battery life, with Nightly builds of the Mozilla-produced browser now requiring as little as a third of the power of the main public release to render web pages.

The Nightly version of Firefox, so-called because it is updated every night, is a testing and development release of the browser that sits between the Developer Edition and the public release. Improvements that are close to being used by normal users are pushed to Nightly in preparation, with one recent addition to the browser helping reduce power consumption for macOS users.
Highlighted by developer Henrik Skupin, users of Firefox Nightly on macOS will see a "huge decrease of its power usage by a factor of about 3x" when loading webpages. The change, which revolves around using CoreAnimation for rendering, cuts down on the amount of power required for the process.
According to data shared in Mozilla's bug ticketing system, accessing some webpages requires between 21 Watts and 30 Watts of power to render without CoreAnimation, with GPU power draws of between 10 Watts and 15 Watts. Under the Nightly build from September 1, the same test pages used 8 Watts and 7 Watts, with GPU usage down to 0.2 Watts for each.
While potentially beneficial to MacBook users, it isn't available for use on the main release of the browser yet, and it is unclear when the benefits will reach that release channel in the future. The inclusion in the Nightly build is a good sign that it could arrive soon, possibly as part of version 70 scheduled to arrive on October 22.
Tuesday's version 69 of the main Firefox release does bring some benefits to macOS users, with MacBook Pro users and those with dual graphics cards will see the browser switch to lower-powered GPUs more aggressively, cutting down on power usage. Also for macOS users, download progress for files is now visible within Finder.
The release's other changes include stronger privacy elements in Enhanced Tracking Protection (ETP) including blocking third-party tracking cookies and cryptominers by default, an enhanced Block Autoplay feature, and support for receiving multiple video codecs.

The Nightly version of Firefox, so-called because it is updated every night, is a testing and development release of the browser that sits between the Developer Edition and the public release. Improvements that are close to being used by normal users are pushed to Nightly in preparation, with one recent addition to the browser helping reduce power consumption for macOS users.
Highlighted by developer Henrik Skupin, users of Firefox Nightly on macOS will see a "huge decrease of its power usage by a factor of about 3x" when loading webpages. The change, which revolves around using CoreAnimation for rendering, cuts down on the amount of power required for the process.
According to data shared in Mozilla's bug ticketing system, accessing some webpages requires between 21 Watts and 30 Watts of power to render without CoreAnimation, with GPU power draws of between 10 Watts and 15 Watts. Under the Nightly build from September 1, the same test pages used 8 Watts and 7 Watts, with GPU usage down to 0.2 Watts for each.
While potentially beneficial to MacBook users, it isn't available for use on the main release of the browser yet, and it is unclear when the benefits will reach that release channel in the future. The inclusion in the Nightly build is a good sign that it could arrive soon, possibly as part of version 70 scheduled to arrive on October 22.
Tuesday's version 69 of the main Firefox release does bring some benefits to macOS users, with MacBook Pro users and those with dual graphics cards will see the browser switch to lower-powered GPUs more aggressively, cutting down on power usage. Also for macOS users, download progress for files is now visible within Finder.
The release's other changes include stronger privacy elements in Enhanced Tracking Protection (ETP) including blocking third-party tracking cookies and cryptominers by default, an enhanced Block Autoplay feature, and support for receiving multiple video codecs.
Comments
I know CoreAnimation is Apple's. Developments like this are amazing to see, particularly for software that's largely been built one way to simplify cross-platform development.
Nightly > Beta > Public
Developer Edition is a modified version of Beta that has additional tools for web developers and is intended for web development versus testing the browser itself. It also uses a separate profile form the regular version so using them side by side is an option.
As of right now:
Nightly is on 71.0a1
Beta & Developer edition are on 70.0b3
Public release is on 69
EDIT: Just found newer info on the exact differences between Nightly/Developer/Beta, from the horse's mouth:
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source: https://developer.mozilla.org/en-US/docs/Mozilla/Firefox
I wish I could use Safari on both but Apple discontinued it on Windows a number of years ago.
So now, on my MacBook I use Safari except when I need to access a bookmark or tab from my Windows laptop, then i jump over to FireFox.