QtQuick/QML allocates too much memory when window is resized

I opened a QtQuick/QML example named "mousearea" bundled with Qt SDK. I built it in release mode and ran it. The memory consumption was initially 13 MB (observed in Windows Task Manager), which is OK. However after resizing the window by dragging the bottom right corner of the window with mouse for a few seconds, the memory drastically increased to about 500 MB. There seems to be a bug which prevent releasing unused memory.