The UK‘s top 50 retail websites are getting slower with third party content to blame, new research has found.

The average loading time for a top 50 retail website was 10.29 seconds in the second quarter of 2014, according to information assurance company NCC Group. This is significantly higher than the average loading time of three seconds.

In just three months the figure has jumped by almost a second from 9.36 seconds. Content was identified as the first problem; page size has increased from 1.44MB in Q1 to 1.55MB in Q2 with third party sites such as ads, social media feeds and systems that track visitor behaviour slowing the system down.

NCC figures show that faster sites tend to use less third-party content. On average, the ten fastest sites loaded content from just four different third-party domains. For the ten slowest sites, the average was 46.

Bob Dowson, director of NCC Group‘s website performance division said: “The wide range of third-party services can be incredibly useful to retailers. They often provide a cheap and convenient alternative when developing an in-house solution would prove too expensive or too time-consuming. However, there is frequently a hidden performance cost. Site owners have no access to those third parties‘ infrastructure and no control over their performance.”

This puts retailers at risk, especially when third-party servers are struggling under heavier than normal load. He explained, “If you‘re using third-party content on your site, the chances are you‘re not the only one accessing it. You therefore need to be aware that a surge in visitors to someone else‘s site could cause your site to slow down.”