It is difficult to tell. Are there 2 Spectro's that night?
If there are 2, then it may be faster on the bus. If there is 1, it may not be. If Spectro is before Wishes, the bus is probably faster.
Remember, if you are driving to MK, you need to factor in either the monorail or ferry time and the tram time.
CBR can be a very busy bus stop and you may need to wait for an additional bus.
Exiting after a parade or fireworks can be a trying time. Any mode of transportation will have a wait time associated with it. You will probably find that no matter which way you go it may take at least 45 minutes from the end of Spectro to arrival at CBR.