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Don’t Underestimate The Importance of Site Speed

Image by tableatny via Wikimedia Commons

Simply put, the faster your site, the more you increase your bottomline. We explore how site speed affects conversions in this post.

As our lives become increasingly busy it is important for companies to react to customer expectation and reliance upon quick and efficient access to data, products and services. In fact Kissmetrics produced an interesting infographic on ‘How loading time affects your bottom line’, which has statistics upon typical user expectations and behaviour.

The graph below shows the audience segmentation per device type of an example client who receive in excess of half a million visitors a month. Over the last year mobile traffic has almost doubled with traffic from tablet devices now at nearly 15% from 10% this time last year:

Traffic Split Chart


The continual creation and improvement to mobile devices means more and more internet users are accessing the internet whilst on the move. We are increasingly seeing cases whereby sites receive a higher level of mobile and tablet traffic than they do desktop, with site speed becoming a more important factor in how the site performs and converts.


What does this change?

Example Client Page Load Time vs Exit Metrics

Above is the exit and bounce rate against page load times for the mobile traffic to an e-commerce site.
Data taken from Google Analytics (July 2013 – June 2014).
Example Client Page Load Time vs Exit Metrics2
 Above is the exit and bounce rate against page load times for the traffic to a lead generation site.
Data from Google Analytics during (July 2013 – June 2014).

Both charts display that the exit metrics are generally larger for pages that take longer to load. Essentially we are seeing that for pages with longer page load times, a larger proportion of users are leaving the site. Based upon the user perceptions and expectations discovered earlier we believe users are becoming frustrated at the underperformance and leaving the site. Additionally, and particularly across mobile devices, users are more likely to be distracted whilst waiting for pages to load.

Why Site Speed Is Important

Site speed is not simply a usability issue, it is an issue that affects SEO, PPC other acquisition channels.

As well as upon mobile devices site speed is important for desktop sites and even a sites ranking position within Google. This has been under much debate with little clear correlation between site speed and ranking but simply put if Google is unable to crawl the site quick enough then it to will be unable to provide the service its users require.


This is why it is important that we are joined up with the other acquisition channels and that we look at Site Speed during Conversion Optimisation campaigns.

Simply put, the faster your site, the more you increase your bottomline. Shopzilla increased their conversion rate by 7-12% after improving their site by just 5 seconds.

How do we increase speed?

• Optimise Caching – Most web pages have resources hosted upon them that do not change frequently, most commonly CSS files, images or JavaScript files. Re-Loading these files each time takes time. HTTP caching allows these resources to be cached by the browser or proxy. Once cached, the browser or proxy can generate the local cached version as opposed to having to download it again each time the page is visited by the same user or device.

• Optimise for mobile – Due to the lesser CPU capabilities of mobile devices, a page may take longer to load on a mobile device. By deferring and/or minimising JavaScript, the pages main content and functionality could be prioritised and loaded much more quickly to reduce the initial page loading time. An additional technique to reduce mobile speed can be to make landing pages cacheable. Often upon mobile devices a user may be re-directed to an ‘m.’ prefixed version of the page, the re-direct takes additional time to load than if the user were to go directly to this page. Therefore caching the redirect will give returning mobile visitors a more seamless, faster experience.

• Reducing HTML File size – Optimising the HTML to include only necessary commands

There are many other speed recommendations at the following sources which have also been referred to in order to compile this document:


Other Helpful Resources

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Phil Gawrylo is Senior Data & Insights Analyst in the data team at twentysix. He enjoys the challenge of unearthing actionable insights from data analysis to help inform the strategy of our conversion rate optimisation campaigns.

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