A high speed parallel manufacturing line for manufacturing insulated glass units, the manufacturing line including a front conveyor system, a back conveyor system, a shuttle mechanism that distributes glass lites to the front conveyor system and the back conveyor system, an insulated glass unit spacer applicator having a spacer dispensing head configured to apply perimeter spacer material to one of the glass lites, the spacer head being proportionally movable relative to the glass lite as the glass lite is conveyed on the front conveyor mechanism to apply the perimeter spacer material to create a spacer applied lite and a gas press. A secondary edge sealing unit has a first secondary edge sealing head and a second secondary edge sealing head, each of the first secondary edge sealing head and the second secondary edge sealing head applying edge sealant to portion of a perimeter of an insulated glass unit.