It is simple physics. Your uphill speed is limited by the wattage you can put out no matter what gear you use. A lower gear will require a certain cadence to maintain speed. If you cannot put out enough power to maintain that cadence in a higher gear you cannot go faster, and you will probably bog down and go slower. Training is the magic bullet that will allow you to climb faster, it will make it possible for you to put out more power and turn that higher gear at the same cadence allowing you to go faster uphill