I think that's about as good as its going to get with the Griots. You might try a red cutting pad and apply moderate pressure, the sides of the pad should bulge around the backing plate, give that shot before you throw in the towel. Even with my PC 7424 which has more torque than the Griots or Ultimate detailing machine, I have to work it VERY slowly, taking at least an hour+ to do the whole car. And does that PC shake, my forearms are numb for a day.
It all depends on the maximum torque of the buffer. I think the Cyclo has the most torque of an orbital without having to step up to a full on rotary. I'm going to trade in my PC for a Cyclo.
Getting out Swirls video (make sure to watch the 'what causes hazing' clip, shows common errors by newbies.