My observations : The banner changed by the fact that, Each item did not have their own individual page, clicking on the item when you enter the banner will not bring you anywhere, this was different compared to COA, which means you can only chose sizes and from the banner and click add to cart.
That aside, I'm not sure if internet plays a part in loading, I'm from Singapore , experimenting with my ultra fast internet in campus and at my normal internet at home. The time taken to checkout took the same. So i guess it's really all about clicking and being persistent if it says item not available