@UnfamiliarLight I haven't yet asked PhaseOne about this. The reason my import took so long was because I was importing a folder from my "NAS" (connected via a gigabit wired network) which contained about 2000 - 5000 images that hadn't yet been imported into C1. My source folder in this case is different from (not located inside of nor is it the parent of) the destination folder, unlike the case with @farbschlurf if I understand his issue correctly.
I can see that in the case of 200 images, the loading might have finished by the time you're done visually inspecting the various settings on the import panel, but in the case of 5000+ images, that loading took a very long time. I didn't time it but I am sure it was longer than 15 minutes.
So to reiterate / clarify my question, say the import dialog only loaded 1000 images out of 5000 total, and I then clicked "Import all" button at that time, would it actually import 5000 or 1000 images? I suppose I can test it, but if it only imported 1000, that's a bug right there.