Memory not released to OS when closing QML window with QQuickWidget

Hello,

There seems to be an issue with memory not being released to the OS after opening a QML view using QQuickWidget then closing window. One would expect that if the window is opened, then closed, the memory used by the application would return to it's starting point if the object is properly deleted. 

However, I am observing that only a small fraction of the memory used for the QML window is returned back to the OS after it is closed. 

Attached is a program which contains the problem. If you click the push button it will open a QML view with QQuickWidget. If you take a look at the memory used by the application before and after opening the QML view you can see that memory does not return to the original value after closing the window. The View is being properly deleted so it is not clear why the memory is not fully released to the OS. 

There are a few videos which show the issue, one I made myself and one from a customer.