Shoppers' definition of "fast" is rapidly changing.
As Amazon Prime subscribers grow more accustomed to two-day delivery, fewer shoppers are impressed by shipments that take any longer to arrive on their doorsteps.
According to a new survey by Deloitte, just 42 percent of consumers characterize three- to four-day shipping as "fast" — down 21 points in just one year.
The severe increase in customer expectations comes as Amazon is rolling out same-day delivery to more markets. Meanwhile, bricks-and-mortar retailers are fulfilling more online orders from their stores, allowing them to cut back on delivery times.
"They had to up their game," said Rod Sides, who heads up Deloitte's retail and distribution practice.