Having finished Disco Elysium I’m not really asking how the movement works - rather expressing my surprise about it appearing as slow.

The characters can run and getting across the whole map from one side to another takes like two minutes of real time. Then you have the aforementioned fast travel allowing you to momentarily move between the three major locations in the game.

Sure there’s a lot of exploration where you have to visit many places and talk to tons of people, but that’s kind of the point of a detective RPG.