Everything You Need to Know about Firefox 3.1

Alex Castle

When we heard today that Apple was releasing a beta version of Safari 4 , which they boast is up to 4 times faster than the previous version, it got us thinking about the new browser wars. More than ever, it seems like every new release from each of the contenders brings with it a bevy of new features and performance upgrades. Although we're excited to put Safari 4 through its paces, right now we're more excited about the next version of Firefox.

Here at Maximum PC, we like Firefox an awful lot. Its mix of stability, speed, expandability and open source warm-fuzzies easily earned it a spot on our recent list of the 32 essential Windows apps . And right now, because we like Firefox an awful lot, it should come as no suprise that we’re excited about Firefox 3.1, the upcoming update from Mozilla. Many of our readers have tried the 3.1 beta, but for those who haven’t, we’re going to take a minute to explain the changes that will impact your browsing experience when the update lands.

New Bells and Whistles

Perhaps the biggest new feature in Firefox 3.1 is the “private browsing” mode, more colorfully known as “porn mode.” Private browsing allows you to temporarily tell Firefox not to save any information about your browsing session. This means that you won’t leave any trace of your activity behind in your history, cache, cookies or saved forms and searches. Naturally, if you choose to create a bookmark or save a file to your computer, those will still remain.

To use private browsing, simply open the Tools menu, then click on Private Browsing. Your current session will be saved and closed, and a new, private session will open. Whenever you’re done, just go back to the Tools menu and uncheck Private Browsing. Your previous session will automatically be restored.

To make your clandestine browsing even easier, Mozilla has also revamped the clear history dialogue, allowing you to selectively delete your history from the last 1, 2, 4, or 24 hours. This is accomplished exactly the same way as deleting history in earlier versions of Firefox, except the menu option is now called “clear recent history.”

The way tabs work has been somewhat revamped, as well. When you click and drag on a tab, you’ll see a ghosted image of that tab’s content hovering under your cursor. If you drag it to another Firefox window, you can dock the tab there, as in Firefox 3.0, although it will do so without having to reload the page. If you release the tab anywhere else, it will assume that you meant to “tear” that tab off, and will open it in a new window.

Under The Hood

That just about does it for the new frontend features, but Firefox 3.1 also has some pretty cool additions behind the scenes that you’ll want to know about.


There are two major improvements to how Firefox handles Javascript. The first is called TraceMonkey.

TraceMonkey is a new JavaScript engine (Firefox 3.0 uses an older engine called SpiderMonkey), which is responsible for huge boosts to Java rendering speed (up to double , in some cases). It was disabled by default in 3.1 beta 1, but is enabled in the second beta release, and will be in the final build. Even if your browser’s Javascript rendering engine isn’t something you frequently concern yourself with, you’ll definitely appreciate the faster user experience you’ll get with TraceMonkey.

The second major improvement is support for worker threads, which allow for multithreading in JavaScript. Primarily, this means that some complicated tasks can be handled in the background, without hanging up the page until it completes. Like TraceMonkey, worker threads are something that will be transparent to most users, but will have a big effect on your browsing experience.

HTML 5 Support: <audio> and <video> tags

Firefox 3.1 adds support for several HTML 5 elements—most significantly, the <audio> and <video> tags. These tags allows site creators to embed (you guessed it!) audio and video inside the browser, without using any plugins like Flash or Quicktime. Although the implementation doesn’t yet have the sort of polish you can get in a Flash-based player, the <video> tag will eventually allow for more flexible integration with JavaScript and other page elements, and should lead to some very exciting new development in video on the web.

New CSS 3 Features

Firefox 3.1 provides support for the CSS @font-face rule, which allows website authors to make certain fonts mandatory to view their page, downloading the font to the reader’s computer if they don’t already have it. This may not seem like the most Earth-shattering change, but it will give site creators an excellent way to make sure that everyone sees their content exactly as they’re meant to.

So when can we expect Firefox 3.1?

Well, if you’re holding out for the final release, you’ll have a little bit of a wait ahead of you. Mozilla hasn’t set a firm release date for Firefox 3.1, and when we asked Mike Beltzner, director of Firefox development about it, he’d only say that “the schedule we’re working against now will likely put us outside of Q1.” Still, you can download and try the beta release right now . In our experience, it’s been very stable (though some plugins won't work), and a noticeable improvement over Firefox 3.0.

Between Firefox 3.1, Safari 4, IE8 and Chrome, the browser wars are really starting to heat up. And with this many competitors in the field, that means very good things for the end user. Look forward to more in-depth browser coverage on MaximumPC.com in the future!

Edit note: Renamed Java section Javascript, and flogged the responsible editor.

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