Some QML items such as QDeclarativeRectangle cache themselves as pixmaps to improve performance. In many cases, when the pixmap is inserted into the cache, the pixmap still has a QPainter open on it and this results in a deep copy when the QPixmapCacheEntry is created because it uses the QPixmap copy constructor. This is most likely not intended since in most (all?) cases, when the pixmap is inserted, the item has already been painted.