First person adds a number of interesting features to the game and it makes sense that it slows down time to the 1x mode.
But it might also be fun to have a "Ride along" mode in addition to a "possession" mode.
In Ride along mode we've got the view that the individual builder has but we can't do any actions. And in Ride Along mode the time isn't slowed down.
There are some great follow camera Mods for Cities Skylines like that and from experience I can tell you they add a great perspective to the game.