Except that managing any number of messages between the max 100 view and the "anything-that-matches-search but you can't actually see them" is not very efficien

Except that managing any number of messages between the max 100 view and the "anything-that-matches-search but you can't actually see them" is not very efficient. In any real desktop mail client, like thunderbird, I can load up and easily skim through all the messages in a folder/label. In Gmail, I can see at most 100 at a time and each load of the next 100 is terribly slow compared to scrolling the message pane in a real mail client and makes actions on the previous 100 unavailable.. This is far from efficient, IMO.