Why does checkout at mall clothing stores take so long?

If I go to Walmart, Target, Ralph's, or any other grocery store and buy 5 items, the cashier scans and bags them all in about 15 seconds. Aldi is even faster. Yet, when the person in front of me buys two shirts at Aeropostale, somehow the checkout process takes 2 minutes. Even if the items don't have security tags to remove, it seems like mall clothing store checkout takes so. Long. What is the cashier doing during this time? Is the POS software just that slow?