Review: Firefox 1.5 Lean, Mean, Even More Secure

In the space of a roughly a year, Firefox has gone from relative obscurity to being the second most popular browser in the world.

It's got only about 9 percent of the Internet browsing market, but that's incredible for a version 1.0 product, especially since the top browser, Microsoft Internet Explorer, comes bundled with new PCs.

The release of Firefox 1.5, the first major upgrade since Firefox 1.0 came out in November 2004, is almost certain to drive adoption rates even higher.

Firefox has not fattened up with its success; it's still lean, mean, fast, and clean. The core application itself is less than 5MB.

By comparison, Internet Explorer 6 Service Pack 1 (including Outlook Express) ranges from 11MB to 75MB depending on which files are needed, according to the Microsoft Web site.

At first glance, Firefox 1.5 (we tested Release Candidate 3 in late November) doesn't seem much different from Firefox 1.0. Everything is where it should be, with the familiar customizable button bars and a tabbed browsing interface.

And in case you're considering a download, 1.5 RC3 is rock-solid. The only complications may be some non-compatible extensions — but we'll get to that later.

The most noticeable improvement in the user interface is the ability to reorder tabs via drag-and-drop. With Firefox 1.0, users had to view tabs in the order in which they were opened.

Navigation is significantly faster, as Mozilla has implemented "intelligent caching" on the forward and back buttons, so the pages one is most likely to visit are preloaded — with no visible performance impact.

User preferences have been redesigned to provide a cleaner tabbed interface, and features are more intuitively arranged.

But the most important Firefox tuneups are under the hood. Application and extension updates are now pushed to the background. This relieves the burden of having to upgrade the application and extensions manually, as with Firefox 1.0, and ensures that the latest security patches are applied.

Mozilla will have the ability to shut down holes as soon as they are found by pushing security patches to the browser. Many of these updates will be, according to the Mozilla Organization, less than 500KB, so they'll be unobtrusive (if noticeable at all).

Our Firefox 1.5 RC2 was background-updated to Firefox 1.5 RC3 with very little impact on our browsing experience.

Firefox 1.5 includes an entirely new extension system, which unfortunately means that many older extensions won't work (Adblock and Forecast Fox worked properly on our test machine). Developers are updating their extensions as you read this, so the updated extensions could be in pretty good shape by the time 1.5 launches. Mozilla has even revamped the extensions-installation system.

Although the process worked well in most instances, the installation, upgrade, and uninstall subsystems were prone to error. When it was installing a new version of an extension, it occasionally left files from older versions behind, which could lead to incompatibilities and browser instability.

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