A person who values their time and hates having to go shopping. "In and out" is the only way they know how to shop, regardless of quantity of items. A power shopper might come across as aggressive and impatient, but they know what they want and where their items are, hence, they see no reason to stroll and dilly-dally and feign that they are thinking of what they want or need to buy.
Power shoppers are known to fill a grocery basket to half-full in under two-minutes. In stores with narrow aisles, they park their cart at the end of the aisle and jog into the aisle, get what they need and toss their items into their baskets from three feet away. They take great pride in always making the basket and never breaking any items.
The man ran his cart into Trader Joe's and began tossing bananas, bags of nuts, loaves of bread and a dozen Clif Bars into his cart. A slow-witted snowbird refused to step aside when he said "excuse me," so he spun around the woman like an NFL tailback, tossed his frozen veggies into his cart and headed back toward the cash register.
A senior citizen commented to her husband, "Did you see how rude that man was?"
The old husband commented, "Nah. He's not rude. He was polite. He said 'Excuse me.' The lady taking up the aisle... who didn't move, SHE was the rude one. I wish I was still young enough to be a 'power shopper,' in my day, I could power shop with the best of 'em.