A typical leading ecommerce website takes longer to render than it did just three months ago, top sites are slower than the rest of the pack, and sites that use a content delivery network (CDN) are slower than sites that do not. These are just a few of the findings detailed in our most recent quarterly research into the performance of the top 500 retail sites.
Background and Approach
Every quarter, we measure the load times for the home pages of the top 500 ecommerce websites (as ranked by Alexa.com) with our eye on a number of performance metrics, including load time, time to interact (aka TTI — the moment when a page’s primary content loads and becomes interactive), page size and composition, and adoption of performance best practices.
The purpose of this research — now available in our Spring 2014 State of the Union for Ecommerce Performance — is to obtain a current snapshot of how retail websites perform for real users in real-world scenarios, as well as gain an understanding of past performance patterns that will allow us to predict future trends.
Here are a few of the top findings from this research:
1. The median top 500 site takes 10 seconds to load. In 2012, the median page loaded in 6.8 seconds, meaning that pages are 47% slower today than they were just two years ago.
2. The top 100 sites are slower than the top 500. The median load time for the top 100 sites was 10.7 seconds.
3. 40% of shoppers will abandon a page that takes 3 seconds or more to load. Yet we found that the median ecommerce page takes 5.4 seconds to become interactive. In other words, visitors must wait 5.4 seconds for the page’s primary content (usually a feature image with a call-to-action button) to render and become usable.
4. 75% of the top 100 sites use a content delivery network (CDN), yet their pages were slower than sites that did not. The median TTI for a page that uses a CDN was 5.7 seconds, compared to the median TTI of 4.7 seconds for pages that do not use a CDN. (Important: This should not be interpreted as an indicator that CDNs are ineffective. The report discusses this finding in greater detail, along with discussion of why the 1-second difference in TTI is a significant one.)
5. Despite the fact that unoptimized images are one of the single greatest performance leeches, many sites fail to take advantage of best practices for optimizing images, such as image compression and progressive JPEGs. (Again, the report contains more details about these techniques.)
Online consumer expectations have not changed: shoppers expect retail pages to load in 3 seconds or less, yet many retail websites fail to deliver this experience. The good news is that this problem is surmountable. Very few of the sites we studied are currently taking full advantage of opportunities to optimize their pages — for example, by following best practices for image optimization.
Our report outlines a number of other best practices that site owners can implement to improve the user experience for their visitors. (Note that these best practices can be applied outside the ecommerce world as well.)