The release of Firefox 3.6 will see Mozilla take the fight back to Google's upstart Chrome.

Review updated: January 26, 2010. See also: Mozilla Firefox 5 review

The Web browsing world is exciting again. Google's Chrome browser is faster than fast and there's serious thought that Internet Explorer may actually lose its top spot in the browser market-share wars. But for all the excitement, it would be a real mistake to overlook Firefox; with the release of Firefox 3.6, which is now available, Mozilla's flagship browser is looking better than ever.

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The just-released final version of Firefox 3.6 is a moderate improvement over previous versions - it's faster and introduces a nifty new feature or two. But at heart, it's the same browser that has steadily gained market share against Internet Explorer for years.

Firefox 3.6 has opened up an even wider speed gap against Internet Explorer, better adheres to Web standards and adds a nice trick or two. Those who favour raw speed alone will still prefer Chrome, but Firefox is clearly superior to Chome when it comes to full-featured Web browsing.

We tested the latest version of Firefox on four machines: one running Vista, one running Windows XP, one running Windows 7 and one running Mac OS X Snow Leopard.

We performed head-to-head testing of Firefox 3.6 against version 3.5, Chrome 4, Internet Explorer 8 and Opera 10 on a Dell Inspiron E1505 laptop with 1GB of RAM and an Intel Core Duo T2400 1.83Ghz processor, running Windows XP SP3.

Firefox 3.6 improved performance

To our delight, we found that Firefox uses considerably less memory after prolonged use than its predecessor, Firefox 3.5.6.

Better memory use may not strike you as the most exciting thing about a Web browser, but if you're a serious Web user, with multiple tabs open at once for hours at a time, it's a big deal.

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We have noticed memory issues with Firefox 3.5.6 that slowed a PC's overall performance.

In our testing of 3.6, these memory problems appear to have been fixed, and that alone makes it a "must upgrade" in our book.

We also noticed that the new Firefox is much faster than the last version. Part of this speed boost comes from Firefox's new ability to run scripts asynchronously.

In the past, Firefox waited for the first script on the page to download completely before running the next script, no matter how long it took to download.

Now, Firefox runs whichever script downloads first, no matter where it's placed on the page. It's one of those small changes that make a big practical difference on pages with multiple scripts.

Using the SunSpider JavaScript benchmark, I found that version 3.6 was faster than 3.5 by 12 percent. It was nearly three times as fast as Opera and nearly four times as fast as Internet Explorer.

But it still lagged behind Chrome by approximately 40 percent. I performed the tests three times for each browser and averaged the results, shown here.

Firefox 3.6 Java web browser speed tests

Even though Chrome beat Firefox by a wide margin when it comes to speed, Firefox appears to be better than Chrome when it comes to memory footprint when multiple tabs are open, at least according to my tests.

With five identical tabs open in each browser, Chrome used 194.6MB versus 100.3MB in Firefox. That is partly by design, though, because Chrome uses separate processes for each tab, which leads to a larger memory footprint when multiple tabs are open.

The upside of this for Chrome (and for Internet Explorer 8, which uses the same technique), is that when an individual tab crashes, only that tab is brought down, and the browser itself remains running. With Firefox, when one tab crashes, it generally brings down the browser.

Firefox has always been bedeviled by poor memory management, particularly memory leaks. In this version, memory management remains somewhat problematic.

When I launched Firefox 3.6 on my Vista machine with a single tab open to Google, it used 57MB of RAM. I opened five more tabs to different Web pages, and memory use grew to approximately 145MB.

However, after I closed down those additional five tabs, and stayed on my initial Google page, it was still using 81MB of RAM - nearly a 50 percent increase in RAM use over when it launched. Clearly, the memory handling problem still needs to be resolved.

NEXT: Firefox 3.6 new features.