I have noticed a GUI issue with File Explorer that is intermittent. It seems to appear at some times, then a Windows update fixes it, then it comes back in another update.

The symptom is a long delay when copying files from one File Explorer window to another.

What happens is this - when the mouse cursor doing the drag passes over the navigation pane on the left side, it usually passes over a drive very briefly. At that moment, the GUI thinks I want to do something on that drive so it pauses a moment to check something, then it goes on again where it left off.

This does not happen if I copy or cut and paste folders.

There may be some internal delay value that is used to avoid this sort of thing and it gets changed every now and then.

I do have a lot of Drives and Volumes, so there's no easy way to avoid passing over them. But I've never been in the habit of copy/paste, so I keep on doing it.

Does anyone know what can be done about this?