The Steam Deck will not boost performance while docked

You may think Valve’s Steam Deck looks awfully like a Nintendo Switch, but they’re actually very disparate designs in a number of ways. Case in point, we’ve recently learned from Valve that the Steam Deck will not perform differently when docked, unlike the Switch. Instead, Valve prioritises the system for how it expects it to be used most: on the go.

That’s not to say you can’t connect a 1080p or greater resolution monitor to the Steam Deck’s dock and have it output at the correct resolution. You absolutely can. However, the performance of the device will stay the same whether docked or mobile, meaning you will experience a performance hit when gaming at higher resolutions in docked mode than in the hand.

source: gamezpot.com