Passengers' luggage is not loaded in an A380 by one suitcase at a time. That would have been very time consuming.
After passengers check in the luggage and head towards the gate where the superjumbo is parked, their baggage is started to get stored in unit load devices1. And after that, those ULDs are loaded into the airplane:
According to Airbus, A380 can store 38 LD3s. Volume of a typical suitcase/bag (dimensions: 32"H x 12"W x 21"D) is less than 5 cubic feet, so 30 suitcases can easily fit in a single LD3.
Now let's talk about your questions about loading and unloading times. As A380s mostly fly on international routes, passengers are required to check in several hours before a flight's departure. But once they check in their luggage, the process of loading those LD3 start, even if the airplane has not yet arrived at the gate. As soon as the airplane reach the gate, unloading and loading processes start. These two processes are not as time consuming as they may appear2.
Passengers' checked in luggage is not loaded like in this manner (picture below). On a wide-body like an A380, this is the case of carry-on baggage which stored in the underfloor area, instead of overhead bins.
1: A380 uses LD3, whose capacity is 159 cubic feet.
2: Note that after an LD3 is unloaded from an airplane, it might take another hour or even more for the passengers to get their luggage at the baggage claim area.