Theoretically it should be faster on twin-aisle. However, you tend to get more passengers/door on twin-aisle planes. A A320 with max 180 passengers is boarded t

Theoretically it should be faster on twin-aisle. However, you tend to get more passengers/door on twin-aisle planes. A A320 with max 180 passengers is boarded through 1-2 doors, a A380 with up to 600 passengers through 2-3 doors. They could use 7 doors for the A380 but no-one is doing that (refuelling and cargo unloading also takes longer). Other long-haul planes are often boarded through only one door (or the second one for <20 premium passengers). That can lead to boarding times of 30 minutes for a long-haul plane, compared to ~10 minutes for A320/B738 through one door (values from experience).