We tested IE9 against the latest betas of Firefox (4.0 beta 6) and Chrome (6.0.472.59). We went for the public betas rather than Firefox nightly builds or the Chrome dev channel as the public betas are designed for everyone to experiment with.

Don't expect an entirely trouble-free experience, though: betas are unfinished bits of software, so the odd crash, incompatibility or outright weirdness comes with the territory. In IE9's case that weirdness appears to be a complete refusal to play nice with Google Docs on our test PC. Office Live, as you might expect, worked just fine.

First impressions

The first thing you'll notice about IE9 is the interface - or rather, the lack of it. Where previous versions filled the screen with lots of buttons and toolbars, IE9 does its very best to hide: everything you need is in a single line at the top.

MINIMAL:IE9's new interface is barely there: Microsoft knows that it's the picture that matters, not the picture frame

It's simple, elegant and effective: back and forward buttons, a combined URL and search box with integrated close, refresh and compatibility mode buttons, your open tabs and then three icons for home, favourites and options.

The combined search and address bar can offer search suggestions, but unlike Chrome's suggestions it's something you have to opt into before your keystrokes are shared with remote servers.

IE9 SEARCH:Microsoft has put search suggestions into IE9, but you need to opt in if you want your keystrokes sent to its servers

The notification bar returns, but it's in a new place - politely coughing at the bottom of the screen rather than bellowing from the top as it used to - and at long last IE gets a download manager. It's no ordinary download manager, though: the final version of IE will use its SmartScreen anti-phishing system as a kind of reputation management system for downloads, warning you of potentially dodgy ones without bugging you about respectable ones.

You also get a Chrome-style New Tab window showing recently visited websites, and in a nice touch coloured bars show how much of your time you've been spending on each one.

Internet Explorer 9 looks very much like Chrome, but that's no bad thing: anything that reduces on-screen clutter and lets us concentrate on the sites we want to see is fine by us. We're not convinced by Firefox's new look, though: it feels a bit thrown together. Perhaps that'll change with future releases.

Features and standards

Both Firefox and Internet Explorer feature hardware graphics acceleration, which promises to boost performance by getting your PC's graphics system to handle some of the heavy lifting. It's coming to Chrome too, but it hasn't made its way across from the developer channel yet.

The reason hardware acceleration is important is because we're doing more and more in the browser, and the line between desktop applications and web applications is becoming increasingly blurry. By giving web applications the same power you'd give desktop applications, they should run much more smoothly.

IE9 is rather keen on its web applications, and in Windows 7 it introduces some clever new features to handle them. If you drag the icon from the current tab to the taskbar you can pin it just like any other program, and when you open it the browser buttons change colour to match the site - so for example if you pin Flickr you get blue browser buttons.

Once you've done that, right-clicking on the icon gives you a jump list, so for example if you've pinned Twitter to the taskbar you get a list including New Tweet, Direct Messages, Mentions, Favourites and Search.

It's very clever and very handy. Firefox and Chrome both support web applications, but not by default: Google's support for apps is only in the developer releases, while Firefox needs Mozilla's Prism to turn sites into desktop applications.

IE9 WEB APPS:IE9-aware applications gain jump lists when you pin them to the Windows 7 taskbar. This one's from Twitter

IE9's support for web standards has been beefed up, too, and it's starting to catch up with its rivals. It supports SVG graphics, WOFF web fonts, HTML5 video (H.264 only) and achieves an Acid3 score of 95%, which is exceptional compared to previous versions.

All three browsers are expandable - Firefox via Add-ons, Chrome via Extensions and IE via Accelerators and Add-ons - and all three offer variations on the Private Browsing theme, but only two of the three browsers have each tab in a separate process.

Misbehaving sites or plug-ins - hello, Flash! - can be killed in Chrome and IE9 without affecting other open tabs, but in Firefox they can still bring down the entire browser.

TABS APART:Both Chrome and IE9 break each tab into a separate process, enabling you to kill a misbehaving plug-in without bringing down the browser

Performance and benchmarks

Let's pretend that JavaScript performance is like running the London Marathon. Chrome always finishes first, Firefox always comes second and Internet Explorer is wearing a chicken suit, wheezing its way through the finish line after the crowds have gone home.

Not any more.

Internet Explorer hasn't just been to the gym: it's munched a whole bunch of energy bars and guzzled a gallon of Red Bull. In the SunSpider benchmarks IE9 whooshes past Firefox and comes very close to catching Chrome, with just 33 milliseconds between Microsoft and Google.

The gap between IE9 and Firefox is much bigger: around 250 milliseconds in IE's favour. That said, we defy you to spot any real difference in everyday web browsing: unless you've got a hopelessly underpowered PC, all three browsers feel equally speedy.

Mozilla points out that SunSpider isn't necessarily the best benchmark to use for browsers - "many benchmarks don't actually do anything," platform engineer Rob Sayre says - and it's developed an alternative, Kraken. As Sayre explains, "We believe that the benchmarks used in Kraken are better in terms of reflecting realistic workloads for pushing the edge of browser performance forward." Naturally we decided to test the browsers on that, too.

Kraken is a much bigger benchmark - it takes around four times longer than SunSpider to complete - and we expected Firefox to do well; let's face it, Mozilla isn't going to go "hey! Come and see Firefox get its arse kicked!"

We also expected IE9 to do badly, because by a handy coincidence Mozilla decided to remind us about Kraken just hours before the IE9 beta went live. Guess what? Firefox did quite well and IE9 didn't.

NOT SO FOXY:We're not entirely convinced by Firefox's new look: it's the least pretty of the three browsers here

Where Firefox and Chrome completed Kraken in around 20,000ms, IE9 needed more than 50,000ms. The bottleneck appears to be the Gaussian Blur test, which takes IE9 around 30,000ms to complete compared to Firefox's 2,000ms.

So what does that actually mean? The short answer is "not much": as Webmonkey points out "Among the real-world things Kraken tests are Mozilla's new beat detection scripts, which uses experimental audio APIs, and image processing tools like the ones that apply a Gaussian blur or desaturate a JPG using JavaScript."

Put simply, Kraken is interested in really demanding web application features, so its scores don't really reflect how your browser will cope with everyday websites.

Here are the numbers:

SunSpider

IE9 566.8ms / 630.4ms
Chrome 6 533.2 ms / 545.8 ms
Firefox 4 823.8 ms / 797.4 ms

Kraken

IE9 52,752.2ms / 57,852.7ms
Chrome 6 20,242.8ms / 20,214.4ms
Firefox 4 19,421.0ms / 19,481.2ms

Verdict

Internet Explorer 9 is quite simply Microsoft's best browser yet, and if the three browsers were all final builds IE would stand a good chance of being our recommended browser on Windows. But there's a problem, and it's a performance problem.

IE9 may be as fast as its rivals but Microsoft's browser development isn't as quick, so for example while we're testing Chrome 6 in beta Chrome 7 is already shooting down the developer channel. IE9 is a great browser today, but if it doesn't ship soon it will be overtaken before it's even started.

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Liked this? Then check out Hands on: Internet Explorer 9 review

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