The Steam Deck will allegedly perform in exactly the same way whether it's docked or not.
In an interview with PC Gamer, Greg Coomer – who helped design Valve's new handheld system – said the team felt it was "actually better, all things considered, to not modify based on docked status or mobile status".
This means that players should not experience a dip in performance if they're playing on the move, which makes it stand out from its chief competitor, the Nintendo Switch.