Black Friday: a disaster for some retail sites while others sailed through

Traditionally, Cyber Monday (the first Monday in December) has been one of the busiest online shopping days in the UK. We were expecting our monitoring data to reveal a few spikes in load times, extra errors and outages as some sites struggled to cope.

However, it looks as though the big retailers actually experienced more disruption on the now (in)famous Black Friday (28 November). Apparently, the stampede of bargain-hungry shoppers in the UK’s high streets was replicated online.

We monitor the performance of 50 of the UK’s top retail sites, nine of which experienced serious performance problems or went down altogether on Black Friday. By contrast, the following Monday saw relatively few problems.

This suggests either that retailers were able to carry out remedial work over the weekend or that the peak in online shoppers on Friday far exceeded the one on Monday (perhaps frustrated consumers gave up on certain sites over the weekend!).

A mixed picture

While the majority of top retail sites actually coped relatively well with the extra traffic, for some it was little short of disastrous. One major clothing retailer’s site was either down or reporting serious errors for much of the day:


Figure 1 – Load times and availability for one retailer. Red bars represent errors, while black bars show when the site was down.

This is in stark contrast to the performance of another retail site, which displayed remarkably consistent performance throughout. wp-bf14-2

Figure 2 – This site’s performance was consistent throughout the busy period

Ironically, one retailer’s dedicated Black Friday home page was responsible for a noticeable slowdown. It doesn’t seem to have had any traffic-related performance problems, but the increase in page size (shown in grey) between Thursday and Sunday coincided with an increase in load times (shown in green/amber):


Figure 3 – A Black Friday offers page slowed things down for this retailer

By contrast, we saw a couple of graphs that looked like the one in figure 4. This company also had a dedicated Black Friday page, but it was a slightly slimmed down version of the standard home page. This meant they actually improved load times over the peak period:


Figure 4 – A smaller dedicated Black Friday page that performed better than the standard home page

All in all, while Black Friday turned out to be pretty dire for an unlucky few, it’s encouraging that most of top UK retail sites weathered the storm relatively unscathed. Our own experience suggests that many organisations are getting more sophisticated when it comes to forecasting, planning and load testing in advance of an expected peak. Hopefully, headlines about websites struggling under load during busy periods will soon become a thing of the past.

Finally, we’d be very interested to hear from retailers affected by the traffic on Black Friday. If you’re one of them, did your site see more visitors than you were expecting? If so, how did you deal with it? Just post a comment below or get in touch with us directly (@NCCGroupWebPerf).


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