Thanks for taking the effort reporting this problem. Can you please provide us with more details on what designer you experience these issues. Is it a Winforms designer or web or something else. What version of JustCode you are using. We have made a lot of fixes that will be part of our next release, especially performance ones, so you may not experience such problems anymore.
Nevertheless ,please don't hesitate to contact us for these or other issues you may have.
the Telerik team
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