Opera Software's beta of Opera 10.5 leapfrogged every rival to become the world's fastest browser, benchmark tests show.

Released on Thursday and powered by a new JavaScript engine, Opera 10.5 beat all comers to easily take the top speed spot.

According to tests run by Computerworld , Opera 10.5 was nearly 15% faster than Safari for Windows and almost 20% faster than Google 's Chrome, the previous No. 1 and No. 2 browsers. Opera's preview was more than twice as fast as Mozilla's Firefox 3.6, over eight times faster than Opera 10.10, and 10 times faster than Microsoft 's Internet Explorer 8 (IE8).

Opera has been an also-ran in JavaScript speed tests for almost two years, ever since developers working on WebKit, the open-source browser engine that powers Apple 's Safari, began bragging about massive JavaScript performance increases . Since then Mozilla built a new JavaScript engine for Firefox, and Google raised the speed ante with Chrome.

The only browser Opera regularly beat in JavaScript races was the even more sluggish IE8.

Computerworld ran the SunSpider JavaScript benchmark suite in Windows XP Service Pack 3 (SP3) three times for each browser, then averaged the scores to arrive at the final rankings.

Opera 10.5 features a new JavaScript rendering engine, dubbed Carakan, and boasts a new vector graphics library called Vega that handles all graphics rendering in the browser. Opera claims that Vega renders graphics about three times faster than the library utilized by Opera 10.10, the company's current production browser.

Other additions to the beta include a revamped interface that reduces the space allotted to menus, support for Windows 7 's Aero Peek and Jump List features, an address bar that brings the history and bookmark search of Firefox's Awesomebar to Opera, and the ability to mark any tab as private so there's no record kept of sites visited or actions taken within that tab.

Opera 10.5's beta is available for Windows only, but alpha builds of the Mac and Linux versions can be downloaded from the Opera Desktop Team blog .

The Norwegian browser maker has not set a ship date for the final of 10.5, but has said that the Windows version will beat the others to that milestone as well. About the time that the final code for Windows is released, Opera will have the Mac and Linux betas ready.

Opera 10.5 beta can be downloaded from the company's Web site.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld . Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com .

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