• While almost half of all consumers browse via their phones, only 1 in 5 complete transactions on mobile (page 5).
  • Optimal load times for peak conversions ranged from 1.8 to 2.7 seconds across device types (page 6).
  • Just a 100-millisecond delay in load time hurt conversion rates by up to 7% (page 7).
  • Bounce rates were highest among mobile shoppers and lowest among those using tablets (page 9).
  • Optimal load times for lowest bounce rates ranged from 700ms to 1.2s across all device types (page 10).
  • A two-second delay in load time hurt bounce rates by up to 103% (page 10).
  • Pages with the lowest bounce rates had start render times ranging from 0.9 to 1.5 seconds (page 12).
  • A two-second delay correlated with up to a 51% decrease in session length (page 14).

1. Background and approach

What this report is:

A semi-annual (spring and fall) study of aggregated performance metrics for leading retail sites. We share performance metrics from three different perspectives – IT, business, and user experience – and explain how they intersect.

How we did it:

We gathered one month’s worth of beacon2 data from leading retail sites, comprised of Akamai customers
who have given permission for their data to be anonymized, aggregated and used in this type of research. Our data science team then used our industry-leading analytics engine to analyze the data.

Why this study is meaningful:

  • It’s the only study of its kind. No other web performance technology provider has the data gathering and analysis tools –and the customer list – to conduct a study like this.
  • This study represents an unprecedented amount of user data. This study represents 27.7 billion beacons’ worth of data – which equates to roughly 10 billion user visits.
  • We have the only analytics engine that can correlate all this data to business-critical user experience metrics and KPIs such as bounce rate, conversion rate, and session length. This gives us unprecedented insight into how performance affects users – and ultimately businesses.What we hoped to learn when we started this project:
  • What is the “magic number” for page load time that yields the highest conversion rate?
  • What is the impact of one second of performance improvement (or slowdown) on conversion rate/bounce rate/session length?
  • How are high-performance pages different – in terms of size, complexity and resources – from pages that perform poorly?

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