Thanksgiving weekend: the truest test of website preparation and performance an online retailer can expect to encounter. It is the culmination of months of strategizing and testing, of not only determining the most jaw-dropping deals, but of ensuring one’s web infrastructure is strong enough to withstand the barrage of shoppers lined up behind their monitors, index fingers poised, ready to begin clicking their way through their gift lists this holiday season.

If a normal shopping day is like peaceful spring shower, rain drops pitter-pattering on a tin roof, think of Thanksgiving night and the days that follow as a level five hurricane with torrents of rain and hundred-mile-an-hour winds pounding the shore, or in the case of e-commerce sites, your servers.

The hurricane this weekend was one for the record books. According to comScore, 57.3 million Americans shopped the web on Black Friday, spending a record $1.04 billion. This represents a 26 percent increase over Black Friday sales in 2011 and the first time Black Friday sales surpassed $1 billion. Online sales on Thanksgiving Day rose as well, climbing 32 percent year-over-year to $633 million.

In past years, such strong numbers have occasionally been tempered by news of web outages or delays that prevented consumers from capitalizing on door-busting sales. However, this year, despite more holiday shoppers hitting the web than ever before, we recorded no web outages or significant performance issues with any of Internet Retailer’s top 50 online retailers. In fact, most e-tailers delivered perfect availability against their SLAs as well as fast response times. None of the retailers we monitored had website speeds that exceeded eight seconds.

Liberty Media Corp, Avon, Sears, and Systemax topped the charts over the Thanksgiving holiday (Thanksgiving night through Sunday night) with the fastest response times of under one second. Meanwhile, retailers including Urban Outfitters, Target, Office Depot, Barnes and Noble, and Toys R Us performed the slowest with response times between six and eight seconds. The chart below includes the average response time and availability for all the sites we’ve been monitoring.

Today, Cyber Monday, is anticipated to be even bigger, with shoppers expected to spend more than $1.5 billion online. Can retailers continue to meet demand with fast load times and high availability? We’ll soon find out.