How to display marquee animation of QProgressBar properly when using it in QTreeView

[Infinity]

As already described, I don't notice a big difference between using persistent editors and not using them. But I tested the application only on Linux (using the QGtkStyle). I will test is on Windows later.

that constantly redraws progress bars

That's true, all progress bars (and not only the progress bars that are currently shown) will be constantly redrawn when I update all values constantly.