Well this is embarrassing. You are right - it is extremely quick. Sorry!
I think I perhaps misunderstood the other recent discussion covering linked rows where we discussed the fact that when you get a Users row via get_user(), any linked rows arrive “empty”, and data has to be fetched.
Maybe that’s incorrect, or maybe in this case the link is fully populated because I fetched the linked row specifically in myRowReference = usersRow['linkToUserDataTable'].