Forget the mad rush of Black Friday. A growing number of Americans wised up, stayed home, enjoyed the holiday weekend, then shopped in a mad frenzy online during Cyber Monday.

According to Internet monitoring firm Akamai, the 270 retailing Web sites it tracks drew more than 4.3 million visitors per minute on Monday afternoon. Akamai’s Net Usage Index (see the index), which monitors North American visitors to Web retailers, was up 39 percent compared with the same period the previous year, according to the company.

The spike is likely a response by consumers to Cyber Monday deals that retailers pushed hard, including free gift cards, free shipping and big discounts, according to a CNNMoney.com report.

Akamai reported a 24-hour peak of 5.1 million North American visitors to retail Web sites at around 8:30 p.m. Monday. Though the frenzy had subsided this morning, Akamai was reporting 2.6 million visitors per minute as of 9:18 a.m., 22 percent above the previous year’s numbers.

Akamai told CNNMoney.com that 88.2 million consumers had planned to shop from home Monday, and an estimated 13.5 million would shop at work. The National Retail Federation estimated 96.5 million Americans had planned to shop online Monday, which was up from 85 million last year.

Cyber Monday is more of a ceremonial start to online shopping, with the busiest online shopping day coming later in December, typically on one of the last days that gifts can be shipped to guarantee delivery by Christmas Day, CNNMoney.com reported.