I'm still on Win10 and in general the context menu loads reasonably fast for me.
But even in WinXP if you had broken registry values it would cause the context menu to load really slowly.
Yeah, when I move files locally, on the same volume. It's real fun watching my Explorer hang when moving files, I have a few hundred thousand files in OneDrive and however they're indexing and tracking them is pretty fucked. And no, it's not the disks.
I'm so done with Microsoft.