The UK’s top 50 retail sites were slightly bigger and slightly slower in Q2 of 2015 than they were in Q1, but render start times improved.According to global information assurance specialist NCC Group, average load time was 12.09 seconds in Q2, compared with 11.43 seconds in Q1. This is more than four times the recommended three seconds (at a testing speed of 2Mbps). Average page size also grew: it was 1.84MB in Q2, up from 1.77MB in the previous quarter.
However, average render start time – the point at which content is first displayed to the end user – was actually faster. In Q1 it was 3.18 seconds, while in Q2 it fell to 2.72 seconds – over 14 per cent quicker. While this is still much slower than the recommended 0.75 seconds, it is perhaps a sign that some retailers understand the importance of starting to deliver content fast. If a web page at least starts to display quickly, a slow total load time need not necessarily mean a poor overall experience.
Ben Daniel, head of the professional services team at NCC Group’s Web Performance division said: “The trend in recent years has been towards bigger, slower web pages, especially in the retail sector. There are a number of reasons for this, with third-party services, custom web fonts and large image carousels all playing a part. This means it’s increasingly important for these sites at least to start displaying content early.”
For the first time, the retail benchmark survey includes Speed Index – a metric that looks at how fast the visible parts of a web page are displayed. A lower number is better, and anything less than 1,000 can be regarded as a “good” score.
In Q2 the average score for the UK’s top retail sites was 5,234. Just two sites managed to score less than 1,000. The site with the best Speed Index score – an average of 817 – also had the fastest average render start time, at just 0.66 seconds, and the fastest average overall load time – an extremely impressive 1.79 seconds.
The other site with a Speed Index score of less than 1,000 was only just behind the overall winner, achieving an average of 866. This is despite the fact that its average total load time was a much slower 3.71 seconds. Although the two sites had very different overall load times, they delivered comparable user experiences.
Ben continued: “Achieving a fast total load time is still a worthwhile goal, but other metrics are now starting to take over, as more sophisticated ways of measuring performance are developed. Speed Index is great because it gives you something you just can’t get from any of the other figures. In general, visitors to your site care more about how quickly a page displays from their point of view than they do about how long it takes every last item on the page to finish loading.”
While this quarter’s figures and the continuing trend towards slower load times are a cause for concern, the fall in average render start time represents a glimmer of hope. It remains to be seen whether this will continue for the rest of the year and whether Speed Index scores will also head in the right direction.
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