Faster startup with many tabs
Previously it could take a while to start Opera if you had many tabs open. In Opera 12 tabs are loaded smarter; fewer at the time with those that are visible or recently accessed loading first. Opera now always starts up equally fast no matter how many tabs you have open.
Out-of-Process Plug-ins
Plug-ins are notorious for causing stability issues. In fact almost one third of all crashes in Opera are caused by plug-ins. In Opera 12 plug-ins are isolated in a separate process, when they crash all you need to do is reload the page.
Experimental Hardware Acceleration and WebGL
Opera 12 contains experimental support for full hardware acceleration and WebGL. While the stability and performance depends on the OS, drivers and graphics card, it is already available for testing. Enabling opera:config#UserPrefs|EnableWebGL allows you to test WebGL content and enabling opera:config#UserPrefs|EnableHardwareAcceleration makes not only the web page but the whole user interface being render via the graphics card. By accessing opera:gpu you can check the current status of Hardware Acceleration and WebGL. Using opera:config#UserPrefs|Preferredrenderer you can switch between OpenGL (0) and DirectX (1).
opera:cpu
Is something slowing down Opera or your computer? You can now easily check with opera:cpu.
Improved loading performance
In Opera 12 the loading of pages has been optimized to ensure that resources like scripts, style sheets and images are loaded more efficiently. The result: Faster loading of pages!
Improved performance on secure connections
When loading a secure page (https) the browser goes through a complex process to establish a secure connection. This exact steps in this process vary from web server to web server, depending on the certificates, version and implementation of TLS they support. For Opera 12 we've analyzed and optimized many of the different steps in this process. Overall many secure pages are now loading faster than before!
RTL
In each release Opera learns a new language. New in Opera 12 is the capability to support Right-To-Left languages which makes it possible to support Arabic, Persian, Hebrew and Urdu. With Kazakh in addition, Opera is now translated into 55 languages.
Improved HTML5 support
HTML5 is the heart and soul of the web. Opera 12 adds support for drag and drop, camera access (getUserMedia), css animations and more.
Improved extensions support
The windows/tabs extensions api has been revamped to include support for access to tab stacks. Check out dev.opera for more upcoming extension features.
64 bit Windows and Mac
Opera 12 is now available in 64 bit for all platforms. Note that because 64 bit applications use more memory than their 32 bit equivalent, the default version of Opera for Windows will continue to be 32 bit.
Do Not Track
Opera 12 enhances your privacy by supporting the "Do Not Track" feature. You can enabled it in Opera's Preferences dialog (Preferences > Advanced > Security > Ask websites not to track me).
Improved address field suggestions
Based on feedback from you we've implemented numerous of tweaks to the address field making the suggested results cleaner, more accurate and more relevant.
New Awesome Themes
Make Opera yours with a whole new set of themes. Design your own or use one of the options we have ready. Change the look of the browser as often as you want — all it takes is one click. You don’t even need to restart!
Discontinuing Opera Unite, Opera Widgets and Voice
