Thank you for writing.
Once you set the CloseAction to CloseAndDispose, GC will dispose the necessary object in one of the next passes.
I guess that your inconvenience is caused by the fact that the Garbage Collector releases the necessary instances later than it frees a less complex control. The reason is that our RadControls are second generation Garbage Collector objects. In case you would like to release the memory instantly after the subform is closed, you can only call the GC.Collect method manually. More information on garbage collection generations can be found in this MSDN article
the Telerik team
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