QML FileDialog slows down application start-up

If you add "FileDialog {}" in your QML code, the application often spends about three seconds more to start. If you additionally set "folder: shortcuts.pictures", the app will spend about 50 seconds to start if running on a device with ~1000 photos.

The reason seems to be that FileDialog creates a FolderListModel upon construction that fetches the entry list of the assigned directory and queries each file for it's size etc. This has a huge penalty especially in the photos case, since then it tries to load 1000 photos into memory and ask for their size.

The solution is probably to do more lazy loading of the qml file dialog until it is actually being used.