However, the big deal may be what you can't see. Preview is running on the same GeckoView engine that underlies Focus, delivering up to twice the speed of regular Firefox -- Mozilla likens the effect to Quantum on the desktop. The company is also keen to tout the independence GeckoView offers. It can deliver high speed without borrowing Google's Blink like many other Android browsers.

The warns that this is an "early version" that doesn't reflect exactly what you'll get when the finished version appears in the fall. And like it or not, the GeckoView tech won't translate to iOS since developers have to use WebKit on Apple's platform. It's still a significant shift, though, and it might give you a reason to use Firefox if you were hoping for a more conspicuous improvement in privacy over rival browsers like Chrome.