By Maggie Shiels
Technology reporter, BBC News, Silicon Valley
About 15% of net users browse the web with Firefox
There is a clear sense of anticipation building at the Mozilla Foundation's headquarters in Mountain View, California where engineers have been working for the past 34-36 months perfecting Firefox 3.0.
"This is the biggest release by far of Firefox," says Mike Schroepfer, vice president of engineering at the non-profit that drives the web browser's development.
"We couldn't have done it without the two million people around the world already running it and the other 20,000 helping give us feedback, working out the bugs and constantly refining it," he said.
Version 3.0 of Firefox is set to debut on 17 June and the Mozilla Foundation aims to try and set a world record for the most downloads in a day when the software is unleashed.
It will have to do well to beat Firefox 2.0 - that version racked up 1.6 million downloads on the day it was first released in October 2006.
Mr Schroepfer said Firefox 3 promised to be faster, easier to use and more secure than rival browsers.
He claims that Firefox 3.0 loads webpages three to four times faster than Firefox 2.0 and more than seven times faster than Microsoft's Internet Explorer (IE).
However, with all manner of factors beyond Mozilla's control affecting browsing speed those claims may prove hard to sustain.
Alongside the speed improvements goes the "Smart Location Bar" - a feature known as the "Awesome Bar" internally at Mozilla.
Mr Schroepfer calls this novel feature: "The biggest user experience change... since tabbed browsing."
Schroepfer: "This is the biggest release by far of Firefox."
The feature gives the browser's address bar a mechanism for quickly returning to web pages without bookmarking them, even if a user doesn't remember the address. It can also search "tags" - keywords that users associate with a particular page.
Security was also high on the development team's list of improvements for the new version.
Mr Schroepfer told the BBC: "It's an arms race between the good guys and the bad guys. This is not scare tactics or boogie man kind of stuff.
"We have seen a huge uptick in malware attacks because they are financially motivated," he said.
"This is billions of dollars a year. There are clear incentives for people to do this because they make money so you need some good guys on your side to block them out."
Included in Firefox 3.0 are malicious software spotters that tell users when they are on a website that has been compromised. A red box will pop up in the middle of the screen warning users of the danger.
Mr Schroepfer said: "This new type of attack where people are hijacking legitimate websites and using them as mechanisms to try and install software on your machine is truly worrying.
Firefox 3.0 warns when users stray on to a booby-trapped page
Behind the warning system is a list of infected sites that is updated every 30 minutes to keep up with the pace of web attacks.
When Firefox 2.0 was launched, said Mr Schroepfer, its security focus was phishing attacks, where fake websites ask for personal details such as bank account or social security numbers to aid identity theft and give access to a user's financial accounts.
"I think people adapted and thought phishing isn't working and then they switched to malware attacks," said Mr Schropefer.
Other features include almost 5000 add-ons to customise a page, making the image on the back button bigger than the forward button because that is the one used more often, and extending how long history stores page information to three months.
Since Firefox launched in 2004 it has gained a steadily increasing share of the web browsing market. Now, on average, about 15% of web users browse the web with Firefox.
"Our goal because we are non profit isn't world domination," said Mr Schroepfer. "It's just to make sure the internet is open, collaborative, competitive and innovative."