As many consumers struggled to button their pants yesterday after indulging in that third helping of stuffing over Thanksgiving, retailers similarly experienced too much of a good thing this past weekend and into Cyber Monday.

Bored, stuffed and quarantined shoppers headed to their computers and smartphones in record numbers over the long weekend to get an early jump on holiday shopping during a year when many retailers are warning that the surge in online sales with the pandemic may result in shipping delays in November and December. That took a toll on site performance at some ecommerce sites.

Fifty ecommerce brands tracked by web optimization software company Yottaa experienced site outages or performance issues during Cyber 5—or Thanksgiving Day through Cyber Monday. The 1,500 ecommerce sites using Yottaa experienced an approximately 60% increase in traffic year over year on Black Friday alone, Yottaa says.

Retailers experiencing performance issues over the last few days include PetSmart, No. 19 in the 2020 Digital Commerce 360 Top 1000, Best Buy Co. Inc. (No. 10), Dick’s Sporting Goods (No. 43), makeup brand MAC, (owned by Estee Lauder Co. No. 69), electronics retailer Micro Center, Toys R Us, Walmart Inc. (No. 3) and apparel retailer Zara (owned by Inditex Group, No. 10 in the Digital Commerce 360 Europe 500). And Yottaa said mid-Monday that shoppers and retailers were likely in for more slowdowns as the day continued.

“We anticipate more brands to have issues on Cyber Monday,” says Bob Buffone, chief technology officer at Yottaa said on Monday. “During previous Cyber Mondays, we often saw desktop traffic surge as people returned to the office for work after the long holiday weekend and took a few minutes during their workday to shop from their office desk. With many people working from home due to COVID, we expect to see much more online traffic and more site outages this Cyber Monday, as workers will have even more flexibility to get Cyber Monday deals during the day on both desktop and mobile devices—without worrying that bosses and co-workers know they are shopping online during work hours.”

Many ecommerce sites have been unable to handle the massive influx of shopper traffic from Cyber 5 holiday promotions, Yottaa says. At other sites, shoppers’ entire carts or some items in them are disappearing. This can happen when retailers place technologies from vendors, such as analytics or personalization software, on their sites, Yottaa says. “We’ve seen third-party technologies that brands put on their sites cause problems, especially on checkout pages,” Buffone says.

 As the shopping commences, the issues begin

Online sales grew 21.5% on Thanksgiving Day alone to reach more than $5 billion, according to Adobe Analytics. And some sites couldn’t handle the traffic. On Thursday, apparel retailer Zara experienced an ecommerce site outage that lasted until at least 7 p.m. Eastern, Yottaa says.

Apparel brand AdidasAG (No. 17 in the Europe 500) also displayed a splash page on Thanksgiving, assuring visitors the site would be “up and running shortly.”

An adidas spokeswoman said any issues were related to the checkout and outside vendor services. “We can confirm that the performance of the adidas website was stable throughout Cyber Week. Adidas did not experience a performance issue, however, depending on their method of payment, some consumers may have faced delays in their checkout process due to a temporary disruption of a third-party service,” she said.

Post turkey shoppers also expressed frustrations with Toys R Us.

Site glitches extend throughout the sales weekend

On Friday, PetSmart’s site was down for many shoppers and was taking 30 seconds or longer to load for other visitors, Yottaa reports.

Pet owners took to Twitter to express their frustrations with the retailer. “Maybe fix your site? Is painfully slow and I can’t add items to the cart,” one consumer wrote on Friday. While another frustrated shopper tweeted: “Can’t shop because the app and website not working. Hope you extending the deals and time because of this inconvenience.” And a third lamented, “Sigh I just want to buy flea meds and the PetSmart site is broken.”

PetSmart responded to many of the tweets saying it was looking into the issues. “We’re sorry to hear that you’re experiencing issues with the website. We’ve shared this with our team to look into, & we’ll resolve this as soon as we can. In the meantime, for immediate assistance, please call 1 (888) 839-9638 to speak with a member of our Customer Care team.”

Beyond direct ecommerce sites, payment provider PayPal Holdings Inc. encountered outages in the U.S. and Europe late Friday morning Eastern, Yottaa says, referencing a map of PayPal outages. Those outages may have impacted brands that rely on PayPal as a payment form. 161 Digital Commerce 360 Top 1000 retailers use PayPal for payment processing.

On Friday evening, apparel retailer H&M (No. 11 in the Europe 500) displayed a note to site visitors asking shoppers to please excuse the wait and promising that its site was doing its best to keep up.

On Saturday, a Digital Commerce 360 analyst encountered an issue at the site of athletic apparel retailer Lululemon Athletica Inc., (No. 54 in the Top 1000) and saw the error message below.

Issues continue into Cyber Monday

As of mid-day Cyber Monday, retailers including athletic footwear and apparel retailer Foot Locker Inc. (No. 45 in the Top 1000), Macy’s Inc. (No. 14 in the Top 1000) and Sears Holdings Corp (No. 41 in the Top 1000) were running into site issues according to Twitter and Yottaa.

Performance slip-ups can add up—especially during the holiday shopping season. For example, 57% of shoppers have left a slow-loading ecommerce site and then bought from a similar retailer, according to a 2019 Retail Systems Research survey of 1,300 shoppers. And 23% said they never returned to a retail site after encountering poor performance.

And retailers say site performance directly impacts conversions. For example, 44% of retailers said improving site load time was critical to improving conversion rates, according to a February 2020 survey of 105 online retailers.  And 43% said improving the user experience was one of their goals for 2020.

Digital Commerce 360 reached out to all brands and retailers cited in this article. No companies except adidas immediately responded to a request for comment or to confirm site performance issues mentioned in this story.