> 3. In Qt, if I overlap 52 QML rectangles like a deck of cards, does the renderer only paint the parts of the rectangles that will be visible in the viewport?

> 3. In Qt, if I overlap 52 QML rectangles like a deck of cards, does the renderer only paint the parts of the rectangles that will be visible in the viewport? I was under the impression that this was the case, but I may be misunderstanding how the Qt QML scenegraph (or whatever it is called) works in practice. The rendering part of the question has been answered in another comment, but I would like to point out a couple things. QML elements are `QObject`s with all the overhead[1] that comes with them. They are created even if they are not visible unless you have some `Loader` or C++ magic to prevent it. A QtWidget `QStyledItemDelegate` only had a single instance for all views/elements that used it. It could scale to millions of "cards" (assuming a QAbstractListModel was used) without any overhead[2]. So even if Qt manage to batch the draws and avoid painting everything, there is still a massive overhead in having such deck. I would suggest using a Loader and keeping only `n` cards loaded. If you want to minimize the performance impact. [1] Object tree management, signal and slots, `n` connections for each QML expressions (recursively down to each tree leafs), memory impact, slower GC, etc. [2] Assuming the model had the lazyloading functions implemented.