Most U.S. and Canadian online shoppers are willing to sacrifice delivery speed for lower shipping costs, according to a survey of holiday shopping released Monday by Purolator International.

Given a choice of fast, more expensive deliveries or cheaper, slower shipping, 55 percent of the American online shoppers polled, and 65 percent of the Canadians, said they "very often" or "always" adjust their delivery date to a longer period in order to obtain reduced cost.

Customers put those beliefs into action last year, with 78 percent of Canadians polled and 58 percent of the Americans opting for shipping that took four days or longer, according to a poll conducted following the 2014 holiday shopping season.

The results run counter to a trend by major retailers to invest heavily in next-day and same-day delivery, whether performing the rapid fulfillment in-house, as with Amazon.com Inc.'s Amazon Flex service, or outsourcing it, as the department store chain Macy's Inc. does with a service called Deliv.

One way online shoppers are cutting delivery costs is by ordering their items sooner, behavior that may explain the popularity of early peak shopping days like "Black Friday" and "Cyber Monday," which occurs today.

Shipping costs are "very important" in shoppers' purchasing and shipment decisions, according to 76 percent of Canadian customers who made an online purchase from a U.S.-based retailer and to 63 percent of U.S. online shoppers, the survey found.

"Cyber Monday provides online shoppers with a tremendous assortment of special offers and sales, and gives consumers the opportunity to shop early enough to attain the lowest possible shipping cost, or even free shipping promotions, from the retailer," John Costanzo, the president of Purolator International, said in a statement.

As a cross-border logistics provider, Purolator predicts that surge of early shopping will result in a peak delivery period for its carriers on December 15, 16, and 17, representing holiday purchases from the previous two weeks.