Microsoft has today unveiled the Internet Explorer 9 release candidate, which is now feature-complete: one last hunt for bugs and it’ll finally be ready.

And our first impressions of the new RC are good. It’s packed with useful tweaks, enhancements and improvements, and proved to be both fast and stable.

One particularly interesting addition is the new Tracking Protection system, which uses a combination of HTTP headers and blacklists to prevent sites from tracking you via cookies, web beacons and other technologies. By default IE9 will block everything it can, but if this causes problems then you’re able to enable content for particular domains. Click Tools > Tracking Protection to access the new controls, then right-click your personalised list and select Enable to turn it on. (You may need to reboot after installation before this will work.)

Another welcome improvement is ActiveX filtering, which blocks any ActiveX content unless you specifically allow it. Turn this on (Tools > ActiveX Filtering) and at first nothing seems to have changed, but if you visit a site that tries to deploy any ActiveX content then a small warning icon will appear in the address bar. If the site works as normal then you can ignore this; alternatively, click the icon and you can enable ActiveX for this site alone.

By default the browser looks much the same, with tabs to the left of the address bar. It’s a space-saving move that works for us, but if you’re less enthusiastic then you’ll pleased to hear that there’s now an alternative. Right-click a tab, select “Show tabs on a separate row”, and they’ll adopt a more conventional layout, appearing just below the address bar.

No browser release is complete these days without a list of HTML5-related improvements, and this one is no different: IE9 now supports geolocation, WebM videos and HTML5 semantic elements, amongst other improvements.

And the release candidate includes a host of performance improvements, from tuning the JavaScript engine, to extending battery life, and reducing memory requirements by several megabytes.

While IE9 proved stable for us, it’s still unfinished, and will contain bugs, so you probably shouldn’t install it on any mission-critical systems.

If you do try the program out and run into difficulties, though, it can be uninstalled via your Windows Updates list. So in Windows 7, for instance, click Control Panel > Programs > Programs and Features > View Installed Updates, scroll to the Microsoft Windows section in the list, select “Windows Internet Explorer 9 Release Candidate” click Uninstall, and IE9 will be removed in just a few moments.

Internet Explorer 9 Release Candidate is available now for Windows 7 32-bit, Windows 7 64-bit, Vista 32-bit and Vista 64-bit.