Sure - here's my scenario exactly...
I create a folder for a shoot on my desktop. Within that folder, I have 3 subfolders: selects, non-selects, and jpegs, all of which are empty to begin with. I dump the shoot from cards to "selects" folder using Finder (I know, I should be using Ingest, but due to a particular and obscure Apple-caused bug that erased one of my cards during ingest two years ago, I still fear it - at the time I was employed at Apple and filed that bug there, ha ha :-)... obviously, they are on the same physical volume, but I would note that my startup disk is partitioned, and that my "desktop" folder is really a separate 100 GB partition unto itself, cleverly put back into it's proper place via symlink (theory being that this is my erasable scratch space so I don't have to contantly fragment the startup volume). I don't believe this Desktop arrangement to be contributing to this in any way - the issue was the same before I came to that arrangement.
I tag or color code a bunch of photos in the selects folder, then I view by tag or color code and do a select all of those photos in the browser tab. At this point, I drag them into the non-selects folder via the Favorites pane. When I do that, I get a progress bar that indicates I'm moving about 1.25 files per second (Canon 5D RAW files), which is of course very slow. The behavior is exactly the same if I drag to the folder via the Navigator pane. This test in version 4.5 final today, but was same last time I checked in 4.4.x as well, and 4.3 before that.... If I drag those same files from the PM browser into a Finder window, the move is instantaneous (as in less than a 10th second).
My machine is 2.66 quad core with 5 GB RAM and experiencing no issues that would contribute to this.