Lag on the N55 DCT is a mixture between the computer saving the clutches for longevity and fuel/throttle cutting to keep the car under control during an initial take off.
If you have ever turned the DTC completely off and then switched to manual/sport mode, jammed on the gas... you would know what I'm talking about. All you do is spin the tires like this.
If you have JB4, do some logs on your laptop. You will see where the throttle/fuel is cut when the pedal is actually being depressed all the way with the traction control on.