Second, Firefox has an important role to play if you care about the value of the web as neutral tech territory -- a place free of the control Apple and Google exert over our phones and the apps we can run on them. Mozilla's mission is to keep the web open and competitive, and Firefox is how Mozilla works to endow the web with new technology like easier payments, virtual reality and fast WebAssembly-powered games.
"Their mission is a good one and does keep pressure up to keep the web open," Gartner analyst David Smith said. He recommended web surfers use "multiple modern browsers."
Mozilla famously undermined the dominance of Microsoft's Internet Explorer when it launched Firefox 1.0 in 2004. But since that triumph, its fortunes have faded. Google's Chrome is now the most-used browser by far, and Mozilla has largely been sidelined when it comes to phones and tablets. Firefox Quantum, a complete overhaul of the browser that took more than a year's work to achieve, is an attempt to start fresh.
"We pulled ourselves up to and in some cases ahead of Chrome," said Mark Mayo, Mozilla's senior vice president of Firefox. "We doubled the performance of Firefox this year. The tentative goal is can we double it again in 2018."
Riding a 'huge upswing'
Even if Mozilla delivers that kind of speed boost, success won't be easy because it's hard to get people to change browsers. Firefox accounts for 6 percent of browser usage today compared with 55 percent for Chrome and 15 percent for Apple's Safari. Narrowing it just to personal computers -- Mozilla's primary focus for the Quantum upgrade -- Firefox has 13 percent to Chrome's 64 percent.
But Mozilla has some grounds for optimism. Usage of Firefox Developer Edition, targeted at web programmers, more than doubled after it was updated to the Firefox 57 version in September. Usage of Firefox Nightly version, a less-stable test version, has nearly tripled in a half year. And social media chatter, while far from an infallible predictor, shows a "huge upswing" in favorable views, Mayo said.
"It's the biggest jump in sustained upswing in sentiment since I've been here," Mayo, who's been with Mozilla for a half a decade, said. That could translate to better market share, he said, though likely not for a few months.
Mozilla says improvements over the last year have stopped defections to other browsers, with about 100 million of us now using Firefox daily. What remains to be seen is whether Mozilla can turn its new performance into more users and thus more leverage to pursue its mission.
What Quantum means for you
Key to Firefox 57's improvements is a project called Quantum that overhauls just about everything the browser does between when it ingests website code and splashes the resulting pixels onto your screen. Quantum, after which Firefox Quantum is named, actually delivered some improvements in the summer, and another big part, called WebRender or Quantum Render, should arrive in early 2018.