Still Firefox 3.5 is well worth the upgrade for the many improvements and additions that will directly affect your web browsing experience. Below is a list of the top 5 new features in Firefox 3.5. Let us know in the comments what you're most looking forward to in the new browser.
1. New JavaScript Engine: TraceMonkey
Perhaps the most hyped new feature in Firefox 3.5 is the addition of its brand new JavaScript engine called TraceMonkey. The new engine promises performance improvements when running heavy JavaScript web applications and pages, such as Google Docs or Meebo. JavaScript speed is hugely important as more and more people are relying on web apps to get things done.
Benchmarks from Technologizer and PCPro show that with TraceMonkey, Firefox 3.5 remains a viable option for web application users. Though not the fastest browser on the market -- that title generally falls with Google's Chrome or Apple's Safari, depending on how the test is performed -- the speed differences are minute at this point. And Firefox 3.5's JavaScript performance is greater than twice as fast as the previous version of the browser.
TraceMonkey definitely brings Firefox up to speed in the area of JavaScript performance.
2. Location Aware Browsing
One of the neatest new things in Firefox 3.5 is its support for location aware browsing. Essentially, you can grant Firefox the permission to figure out where you are based on your IP address and nearby wireless access points, which the browser can then relay to web sites in order to provide you with a more personalized browsing experience.
A national pizza chain, for example, could offer you coupons for your local franchise based on your location, or a new site could deliver you the latest information from your neighborhood. For a real life example, check out Flickr's map page, which uses the new geolocation tools in Firefox 3.5 to determine your location and then show your photos from other people in your area.
Though it sounds potentially Orwellian, location aware browsing is fairly benign when it comes to your privacy. Firefox only shares your location with sites you've approved to have access to it, and their default geolocation service provider, Google Location Services, deletes the random client identifier assigned to you after two weeks. Firefox doesn't provide any information about the web sites you're visiting or your cookies to requesting sites or to Google. Still, the feature can be turned off.
3. Support for HTML 5 and Downloadable Fonts
A lot of the new stuff in Firefox 3.5 is support for new web technologies that only web developers will really geek out on. But some of those new technologies, like HTML 5 and the CSS @font-face rule, will have a noticeable positive effect for users.
HTML 5, for example, includes audio and video elements that allow developers to embed media directly into HTML pages in a similar way that can now be achieved with browser plugins like Flash. Currently, Firefox 3.5 supports HTML 5 audio and video with Ogg Theora, Ogg Vorbis, and WAV formats. Firefox 3.5 also offers support for the canvas element in HTML 5 that lets developers create scriptable bitmap images -- or in other words: animations. Check out the Canvas Demos site for a taste of the cool things possible with canvas.
The CSS @font-face rule, meanwhile, lets designers link fonts to web pages using CSS. That means that web designers can create pages that go beyond the limited "web-safe" fonts, which opens up the possibility of web page designs that use any font, regardless of whether it is installed on the viewer's system.
4. Fun with Tabs and Windows
Since Firefox 3.0, users have been able to recover recently closed tabs by pressing ctrl+shift+T. But that implementation was fairly limited -- it only opened the last closed tab, and it didn't apply to accidentally closed windows. Firefox 3.5 adds two new items to the History menu: Recently Closed Tabs and Recently Closed Windows. They do just what they sound like they'd do: they let users choose from a list of recently closed tabs or windows and reopen them.
Another new tab related feature of Firefox 3.5 is tab tearing, which also exists in Google Chrome. Tab tearing lets you rip a tab out of the current window into its own dedicated window -- it sort of works in reverse as well, if you move the last tab in a window back into a collection of tabs, the window disappears. You can't merge a window with multiple tabs into another, though, unless you do it one tab at a time.
5. Private Browsing
One of the few areas where Firefox is playing catch up is private browsing. It's a new feature in Firefox 3.5, though it has already been available in Chrome, Safari, and even Internet Explorer.
In private browsing mode, Firefox doesn't save your browsing, search, download, or web form histories, or your cookies, or temporary Internet files. Remember, though, that private browsing doesn't mean anonymous browsing -- your ISP might still have a record of where you've been, and if you log into any sites, they might still have a record of who you are and when you were there.
When you first start private browsing mode, Firefox hides all open tabs and saves them for later. It's a little scary to see all your tabs disappear the first time you use it -- I didn't read the warning Firefox gives, so nearly panicked thinking that Firefox had restarted and I'd somehow lost all my open tabs (which contained a lot of research for this post).
Firefox 3.5 also includes a bit of retroactive private browsing as well, in the form of the new "Forget About This Site" history command, which tells Firefox to erase that site from your browser history. It doesn't accomplish much, but it makes it easy to erase a specific site from your history without having to erase the entire thing. Firefox also offers Google Chrome-esque history management options by allowing you to set a time range when you clear history items like your browsing, download, and form history, or your cache or cookies. You can choose to only erase new information saved from the last hour, two hours, four, or full day of browsing, or erase everything.