Google Chrome for Mac may as yet lack some features of the Windows version, but it is a very fast web browser. UPDATED December 9 2009.

Just when you thought there were already too many Mac OS X browsers - Safari, Firefox, OmniWeb, Camino, iCab, and Opera, to name but a few - one more enters the fray: the beta version of Google's browser, Chrome for Mac.

So what does Google Chrome for Mac bring to the browsing experience, and are there any features that might make you consider switching from your primary browser?

First, before you consider switching, realise that Chrome is very much a beta release on the Mac. As covered earlier, Google Chrome for Mac is missing many features found on its more-advanced Windows counterpart, including major items such as a bookmarks manager and support for extensions, along with less-obvious features such as multi-touch gesture support, 64-bit compatibility, and support for Google Gears and standalone browser applications, like those you can create using Fluid.

Beneath these stated omissions, digging into Google Chrome for Mac's preferences reveals additional not-quite-there-yet features. You can't view your cookies (though you can change your cookie acceptance settings), change auto-opening settings, change fonts and language defaults, or manage your SSL certificates. All of these things are coming, but they didn't make it in time for the beta.

There's also a grayed-out button for importing settings for other browsers, so you might think that's not functional, either. This feature actually works; you just have to access it through the Chrome -> Import Settings and Bookmarks menu item, not through the button in Chrome's preferences. At present, Chrome can import history and bookmarks from Safari; you can import the same from Firefox, plus cookies, saved passwords, and search engines.

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Google Chrome for Mac: the interface

So with all that's missing what is there that might compel you to take a look at Google Chrome for Mac? The first thing we visually noticed is the tabs-on-top (almost) layout, along with just one input box, which Google calls the OmniBox.

If you type a URL in the OmniBox, Google Chrome for Mac opens that site. If you want to search the web, just type your search query in the URL box, and Chrome will send that query to Google. (At present, there's no way to set the default search engine, although that ability exists in the Windows version, so it's probably coming in a future Mac release.)

Although we weren't a fan of Safari's tabs-on-top experiment, we like the Chrome implementation - the tabs aren't completely on top; a small window border lies above the tabs, so you can drag the window around via the top edge. This combination allows for maximum screen real estate for the browser window while still allowing easy movement of the Google Chrome for Mac window.

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As you'd expect, tabs are quite flexible; they can be dragged around the tab bar, off to form a new tab, or you can merge windows by dragging one window onto another's tab bar. Each tab includes its own loading progress and close indicators. Tabs resize as you add more, and the algorithm works well - we were able to recognise tabs even with over 15 open in a not overly wide window.

While Google Chrome for Mac lacks a bookmarks manager, you can bookmark a site by either dragging it to the bookmarks bar, or clicking the star next to the URL. Once saved, you can remove a bookmarked site by first loading it, then clicking the star again.

One thing we really like about Google Chrome for Mac is that when you add a bookmark to the Bookmarks Bar, it uses the site's favicon in the bar, with no accompanying text. We can fit a ton of sites on the bookmarks bar, and they're all easily distinguished.

If you prefer to see text, too, you can add it by Control-clicking on a site in the bookmarks bar and choosing Edit from the contextual menu.

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Google Chrome for Mac: Speed

Chrome is a very fast browser, both in subjective feel and objective performance tests. It feels fast because the interface reacts quickly to your actions, and page loading starts seemingly immediately after entering a URL. Even little things, like dragging a tab, feel much more responsive in Chrome than they do in Firefox. Ask for a new window or tab, and it appears instantly. User perception can be more important than actual measured speed in a browser, and the perception in my time with Chrome is that it's fast.

In this case, though, the numbers back up the perception. We ran eight browsers (Firefox 3.5 and 3.6b4, Safari and WebKit, OmniWeb, Camino, Opera, and Chrome) through two different performance tests. The SunSpider JavaScript Benchmark attempts to measure real-world JavaScript performance, using features that sites are using today. We also ran each browser through the Peackeeper browser benchmark, another JavaScript-based test.

Based on these tests, the fastest browser of the bunch is WebKit, the open source core of Safari. Safari and Chrome, both built on WebKit, basically tied for second on both tests. The remainder of the browsers, were much further off the pace, with scores ranging from 2x to 10x worse than Safari and Chrome. JavaScript tests aren't the only measure of performance, of course, but these results back up the perception that Chrome is a speedy browser.

Google Chrome for Mac: Tabs as processes

One of the key features of Google Chrome for Mac is that separate sites are treated as separate processes by the browser - that is, you can think of each tab or window you open as a unique application, even though they're all running in Chrome. The benefit, as a user, is that if a site crashes, it will only kill the particular window or tab that it's open in; everything else will keep right on running - you can switch to other open tabs, open windows, and do anything else you might normally do.

Treating each site as a separate task a great improvement, and is probably the single strongest reason to use Chrome over the other OS X browsers - no longer will you lose all your open tabs just because of one troublesome site.

When Google Chrome for Mac detects a tab has crashed, you'll get a nice pop-up window to let you close the troublesome page.

The down side of treating each site as a separate process is that you can chew through memory in a hurry. As a simple test, we opened the same five sites in Chrome and Firefox 3.5, and compared the total real memory usage in Activity Monitor. Firefox used 172MB of RAM to open the five sites; Chrome required more than 275MB. If you work with a lot of open tabs and windows, you'll want to keep an eye on your memory usage; all the speed of Chrome isn't worth anything if you use up your RAM and start using virtual memory.

The extra memory usage, though, is worth it the first time you don't have to reopen 15 tabs after some Flash game... er, important research site crashes your entire browser.

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Google Chrome for Mac: other features

Google Chrome for Mac includes incognito mode, which prevents the browser from recording your browsing habits. One nice feature in Chrome is that you can enable incognito mode on a given window, instead of having it be an on-or-off setting, as it is with Safari's Private Browsing mode.

If you're not enamoured with the default Chrome look, you can install themes that change the look of the header, buttons, and various other interface elements.

There are themes by third-party artists, as well as by Google. Personally, we're a fan of the simple look, but if you want fancy coloured backgrounds in your header, you can have them (and importantly, they're very easy to uninstall, too).

Finally, if you look at source code from web pages, Google Chrome for Mac does a reasonably good job of cleaning it up - you not only get line numbers, but the HTML is syntax highlighted (comments in green, URLs are clickable hyperlinks, HTML code is purple, etc).

NEXT: our first look at a prerelease build of Chrome for Mac, from June 09 >