They donīt play, no schedules are generated, no games played, teams donīt need a full roster, ... (I know that because I coded it
). Player stats creation (which is important for development) takes only seconds. The big difference between setup one (full game with NHL/AHL playable) and the second setup (fictional setup with real NHL/AHL) is the player DB: the first one still has roughly 100.000 players active (+ a few 10.000 retired players as well), the second scenario has only a few hundred players.
So you have 3 options:
1. Play with everything and accept that it takes a while to simulate.
2. Play with just a handful of leagues that interest you and you get a much faster game.
3. Play with a real-2018 NHL/AHL/(CHL) setup which is very fast.
Should be something for everyone in my opinion.