One of my external drives (WD My Book) works very slowly when I try to copy/paste files in it or from it. And it happens when I open the folders as well.
It’s an USB 3.0 device and I tried in USB 2.0 and 3.0. And in different computers.
It seems that it depends on the zone of the disc where the files are copied/pasted.
WD Smartware doesn’t help.