By Bob Dowson, director of NCC Group’s Website Performance division

As a retailer, you would want to know if long queues were driving thousands of customers out of your shops.

You would expect to be told if all your stores had to close on the busiest shopping day of the year.

You wouldn’t put up with it in the real world.

You shouldn’t put up with it online.

However, in our experience, many organisations do.

Britain’s retail sites are getting slower on average. Every day, we come across major sites that fail to abide by basic web performance guidelines. And if visitors have to wait too long for a page to load, many will leave.

Why do site owners let this happen?

As a discipline, web performance is pretty niche. It’s also relatively new. We’re now starting to get more sophisticated about how we think about and measure performance, but the message about why it matters is taking a while to get out there.

This is despite the fact that studies linking performance to key metrics, such as conversion and abandonment, have been around for some time.

How load time affects revenue

One of the best-known studies was carried out by Walmart in 2012.

This showed a direct link between load time and conversion2. Average load time for the converted population was 3.22 seconds. For the non-converted population it was 6.03 seconds. Walmart also found they were able to grow revenue by 1 per cent for every 100 milliseconds cut from load time.

Search engine optimisation

Load time also has an indirect effect on a site’s success, and people are often surprised to learn that speed is a factor in search engine ranking for Google. In fact it has been since 2010: a website’s performance matters both to organic SEO and to Google’s quality score for Adwords.

It now looks as though Google is thinking about taking this a step further and labelling slow sites in search results pages.

Staying out of the news

Web performance is often seen as a purely technical matter. Something for the IT department to look into when they get a moment. Only rarely does it find its way into the boardroom. And when it does, it’s often too late. Because a poorly performing website is more likely to fail under load.

When traffic is high, your website may be at risk of slowing down or, ultimately, failing altogether. And if your site collapses, you’ll hit the headlines for all the wrong reasons (remember the problems that plagued healthcare.gov in the US?).

A website that’s optimised for performance is generally smaller and makes effective use of browser caching. As a result, less data needs to be transmitted, which in turn makes the site far better able to cope with surges in traffic.

Cost and efficiency

Performance improvements are often focused on maximising revenue, but there are cost savings to be made as well. Again, this is partly because fast web pages tend to be smaller: just as a small car tends to burn less fuel, a smaller web page uses less bandwidth – which is very important if you pay for what you use.

Failing to optimise a site for performance can also mean you’re investing in hardware you don’t need. Make your site smaller and more efficient, and you could find that your IT budget goes much further.

Why isn’t everyone doing this?

As we mentioned earlier, knowledge is one factor. Web performance doesn’t get much in the way of publicity – except when things go very wrong. And since it can be a fairly technical subject, the people who do know it’s important tend to be fairly technical people.

But for performance to gain traction within an organisation, a much broader range of people need to buy into it: if it’s not given some air time at board level, it can all too easily get overlooked.

Part of the answer, then, involves making performance data more accessible. Presenting all the technical detail in the board room will be counter-productive. Instead, making sure that performance benchmarks and KPIs are featured in regular management reports is far more likely to be effective.

Ultimately, it’s up to C-level executives to lead the charge and create a culture of performance within the organisation. And this is starting to happen. While Britain’s retail websites might be getting slower overall, there are one or two trailblazers who are bucking the trend and reaping the rewards.