Mozilla Firefox 3.6 (Release Candidate)

The release of Firefox 3.6 will see Mozilla take the fight back to Google's upstart Chrome. This review is of a Release Candidate version (January 2010).

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 forthcoming release of Firefox 3.6, which is now available as a release candidate, Mozilla's flagship browser is looking better than ever.

As soon as the release candidate came out on January 9, I started putting it through its paces, using two Dell 530S desktop PCs.

These older computers are powered by a 2.2GHz Intel Pentium E2200 dual-core processor with an 800MHz front-side bus. Each has 4GB of RAM, a 500GB SATA (Serial ATA) drive, and an Integrated Intel 3100 GMA (Graphics Media Accelerator) chipset. One was loaded with Windows XP SP3 and the other used MEPIS 8 desktop Linux.

Firefox 3.6 improved performance

To my delight, I 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.

I, and other users, have noticed memory issues with Firefox 3.5.6 that slowed a PC's overall performance.

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

I 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.

In particular, Firefox 3.6 does much better with Web 2.0 sites that rely on JavaScript. With its updated JavaScript engine, TraceMonkey, I found that the browser was more than three times faster than Firefox 3.5.6 on the SunSpider JavaScript benchmark test.

On the Windows XP system, Firefox 3.5.6 came in at a poky 3034.4 milliseconds, while Firefox 3.6 zipped by it at 1007.0 milliseconds.

That's great, but it still leaves Firefox lagging behind Chrome, which easily lapped the field with a time of 553.0 milliseconds.