Heating and cooling supply vents are almost never installed right which is costing you money. First, the vent should be sealed off during construction to prevent debris from falling into the opening, but also for job site safety. This will prevent blockages in the duct from various debris to block air flow.
The vent should also be tied tight to the subfloor using mastic. This reduces the amount of air that will hit the bottom of the register and flow back down into the room above or below. This allows the air flow to work closer as was designed.