This could be the animation timing for scrolling which, i think, is at 100ms at the moment. I haven't looked in the source. If you have a folder open in preview icon mode and large thumbnails (say 128px) then scrolling seems to "jump" a few lines. That causes me to always have a hard to finding the file as it feels very unnatural. It's not only in dolphin, it's also in file open/save dialogs.
*** This bug has been marked as a duplicate of bug 386379 ***