The vertical scrolling using the mouse wheel is slow. It happens on two separate installations. KDE is set as default to scroll 3 lines at a time. It seems it needs two full scroll gestures (meaning moving the mouse wheel scrolling from its front to the back, on the entire length of its visible part) in order to scroll a line of text. This is common to all the panels except to the files and folders view.
Thanks for report, hopefully this will be fixed in Dolphin 16.12 *** This bug has been marked as a duplicate of bug 365968 ***