I have replied to the support ticket.
The GridView in the sample project is placed in a stack panel which means it is measured with infinity(GridView needs an exact number to be measured with in order for the UI virtualization to take any effect), hence it creates rows for every single item in the ItemsSource. In this case, a high memory consumption is expected. Still clearing the items source releases the memory.
Would it be possible to provide some more details about your scenario. What is the exact binaries version you are using. The support info indicates 2014.3.1202. is that correct? What is the OS version in which you are observing the problem?
Furthermore, a snapshot from a memory profiler would be very helpful in the process of finding the source of the problem and providing a solution.
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