RadControls for Windows Phone 7.x have been upgraded to use all the benefits that come with the Windows Phone 8 operating system. You can upgrade your project and swap the Telerik libraries with the ones that target the Windows Phone 8 OS and you can be sure that you will get the expected performance.
If you experience any issues while transitioning, do not hesitate to get back to me so that I can help.
the Telerik team
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