QML GridView scrolling is janky

[Michel de Boer]

I have a GridView (QML) with 3 colums to show square thumbnail images on a mobile phone (Android). The scrolling is not smooth. It is janky.
I have already set the image sourceSize to the size of the grid cells to avoid a large amount of image data in memory.
Also image loading is asynchronous (via HTTP).

Even when I replace the images by rectangles, the scrolling is still a bit janky, but less so.

I have added logging to a QGuiApplication::notify (in a subsclass) to see how much event handling takes. I notice that QEvent::updateRequest sent to my ApplicationWindow often takes more than 16ms to process. That seems too much to get smooth frame rendering.

Any idea, how to speed this up?