In the same road tire, higher pressure will run faster since the higher pressure will reduce the contact patch. But as roads aren't usually smooth, past a certain pressure the resulting road vibration can create greater fatigue slowing you down and make the bike less stable/more bouncy over rough patches requiring slower speeds. Optimal pressure is based on your weight, tire size, materials, rim size, and road conditions. Strictly road I don't have any tire under 35mm I run at under 80psi for myself or under 70psi for my wife.