Firefox 4 is out in the wild and you can check out our Firefox 4 review now.

Ahead of the launch we met with Jay Sullivan, Mozilla's vice president of products, and Tristan Nitot, the founder and president of Mozilla Europe to learn about its hopes for the new browser – and how Mozilla deals with the huge amount of feedback it has received on the browser.

Both are old hands in Mozilla, having been involved since 2007 and 2001 respectively and they talk candidly about their involvement and thoughts on Firefox and other players.

"Firefox has 400 million users and 30 per cent market share," says Nitot. "Being non-profit we're mission-driven.

"We do need to be sustainable long-term but our mission is to build a better web," he says, forcing home the point that, unlike Google, Mozilla sees itself as more of a curator than money-maker.

"The web is a global shared resource and we want to take care of it rather than monetise it."

There are two key points of interest with Firefox 4 – firstly, the speed improvements and, secondly, the mobile version which will be primarily available for Android.

"With Firefox 4, you'll notice the speed compared to 3.5, 3.6 and 3.0 and there's a full new user interface," explains Nitot. "We have a mobile version of Firefox 4 and you can completely synchronise them and share history and your open tabs."

Using user feedback

Then, Sullivan gave some insight into how Mozilla deals with the huge amount of user feedback it receives – and how unique it is as a project:

"There is no shortage of opinions. Mozilla is this fascinating work in progress. No other open source project has been a user experience project, [others are] all server stuff, there's no UI.

"We have about 50,000 people who use a new build every day and about 2.5 million beta users. We got about two million individual pieces of feedback."

Giving a case in point, Sullivan referred to the tabs – which have moved right to the top of the window in Firefox 4. "The debate about whether the tabs should be top or bottom [of the awesome bar] has been on our Wiki for about three years."

"We also did some experimentation with merging the status bar into the URL bar. When we launched that we got a bit of feedback like 'we understand the innovation here but I'm used to looking in the lower left for this stuff, just leave it there'.

"You just have to ride these out because a lot of people don't like change, but in that case it was overwhelming enough to say 'that's what they want'. A lot of the time you have to lead people, but you can't be arrogant either.

"When we made the back button bigger [in Firefox 3], it was because we did usability studies that showed that 95 per cent of people clicked on the back button and five per cent on the forward button," explains Sullivan. "That got copied by IE and others."

Chrome and IE9 may be quicker in terms of paper benchmarks, but Mozilla is confident that Firefox is competitive - something we found in our IE9 vs Firefox 4 vs Chrome 10 piece.

"I think we've a more balanced approach. Chrome has gone for raw speed and now we've got this too and we've got all this other stuff, customisation, HTML5 support and the most seamless experience included encrypted sync."

Indeeed, the synchronisation is extremely good, although it doesn't transfer your add-ons in the same way that Google Chrome will sync Extensions.

Going mobile for speed

Sullivan attributes the "real impetus" for a faster browser was when it looked at designing the mobile version of the browser to run on ARM chips.

"So our target was 500MHz ARM chips and [Intel] Atom chips - really slow. That caused us to do a lot, optimise it for JavaScript. We have a new concept called compartments and basically when you garbage collect [JavaScript objects] you can do it without pausing the whole browser.

"We really wanted to create the best browser for Android phones with full sync. It's powerful."

Speed has been increased on the desktop in areas where Firefox 3 was causing system overload. "When pausing happens when switching tabs or windows, we've really reduced those," says Sullivan.

"We've also greatly enhanced the way we do disk I/O when you start up, as well as the way you load tabs when you start up. We're going to load the tab in your face, then your app tabs, then your background tabs when the CPU is idle."

"We're doing a massive list of those things much more efficiently. We have a new graphics architecture called layers and what that does is represent the layers of your webpage - so we're not repainting them all the time. They're composited using hardware acceleration.

"We just went really hard after performance and running on mobile really helped. Running on these things [Sullivan points at a PC] really spoils you and when you have to run on mobile you start looking for every little thing. It really focuses the mind.

"2011 will be the year of multi-core phones and when you run a WebGL thing on that it's extremely fast. From a JavaScript point of view, we're fighting over scraps, we're all fast. And that's where I think Firefox is still the best – getting smoothly from tab to tab."

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Liked this? Then check out Best browser 2011: which should you be using?

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