Hi Stanescu Mihai,
You can try playing with the visibility of the CoverFlow control. This should point you out whether the issue comes from the CoverFlow control rendering or something else. Meanwhile we are researching the issues, and do our best to reproduce it. If your case is easy to isolate, we would be more than happy to investigate the issue right out of your project. In this way, we will at least give you some hint how to minimize the performance issues you face.
Thank you for contacting us and we look forward to resolving your issue as soon as possible. And take our apologies for delaying this issue so much.
the Telerik team
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