What exactly are you observing?
Post some numbers or scopeviews to make things more exact.
Large power and high wattage would be the same thing, high voltage something else.
How is your capacitor going short circuit?
Connecting an uncharged capacitor to a voltage source could result in a large inrush current.
And connecting the charged output capacitor of the power supply to a low impedance load could cause a high discharge current.