I've tested it a little more to figure out when the Apple-W doesn't work well. It seems to happen most often when I have more than one contact sheet up in tabbed windows. I'll hit Apple-W and nothing will happen or I'll get the error chime (the one that you get when the key press isn't registering). If I hit it again, the window will close. It seems that it's only the first time I try it with the open windows. It will work normally from then on until I close those contact sheets and open new ones. So it's not life or death, just annoying.
As for the time window coming up and working slowly, I was using 4.4.3.3. I still have it on my system, so I tried tagging 10 photos from each version. The time dailog box only comes up in the new one (briefly for 5 pics, more time for 10, but not bad). It doesn't come up at all in the old version. It may be my imagination, but it seems faster in the old version.