Application Acceleration & OptimizationApplication Delivery

Case Study: Understanding the Impact of Slow Load Times on Shopping Cart Abandonment

October 31, 2013 — by Tammy Everts19

Every year, the shopping cart abandonment rate climbs during the holiday season, with analysts expecting to see a peak of 88% in 2013. An estimated one out of five of those carts are abandoned due to slow performance.

This post outlines how much retailers lose due to slow checkout pages, four common performance culprits, and what site owners can do to speed up the transaction process for their customers.

Online shoppers today are more likely than ever to abandon their shopping carts — even after taking the time and effort to browse and fill them. Though abandonment rate numbers vary throughout the year, roughly 75% of online shopping carts are abandoned before checkout. This number has risen every year since 2006, and as already mentioned, tends to peak during the holiday shopping season.

Shopping cart abandonment 2006-2013

Why do shoppers abandon their carts?

There are a number of reasons for shopping cart abandonment:

  • Saving items to buy later
  • Finding a better price elsewhere
  • Realizing that items or amount didn’t qualify for free shipping
  • Discovering that shipping costs were too high
  • Slow checkout pages

This last point is the basis for today’s post: 18% of shoppers will abandon their cart if pages are too slow.

How much do online retailers lose due to slow shopping carts?

The total cost of abandoned shopping carts for online retailers has been estimated at more than $18 billion per year. If 18% of that loss can be attributed to slow pages, then this correlates to more than $3 billion in lost sales (across US ecommerce sites) due to poor performance.

These losses don’t just affect a shopper’s current visit, but future visits as well. In one survey, 44% of online shoppers reported that when a checkout page takes too long, they worry about the success of the transaction (e.g. Were they double billed? Were they billed but their order wasn’t processed?). This is why shopping cart speed doesn’t just affect the current transaction, but potential future transactions as well. In fact, 46% of online shoppers cite checkout speed as the number one factor that determines whether or not they will return to a site.

Case study: Impact of checkout slowdown on cart abandonment

We worked with an ecommerce customer who wanted to experiment with the impact of page slowdown on a multi-step transaction. We conducted a split test in which traffic was divided into three groups and each group was delivered a different user experience across a five-page transaction. We found that just a 2-second delay in load time during checkout resulted in abandonment rates reaching as high as 87%.

  • For group #1, we delivered a fully optimized set of pages via our FastView solution. This established that the site’s baseline abandonment rate was 67%.
  • For group #2, we introduced a 2-second slowdown to the third page in the transaction. The abandonment rate increased to 80%.
  • For group #3, we introduced a 2-second delay to the first page in the transaction. For this group, the abandonment rate increased to 87%.

While the impact of slowing down pages in the checkout process varies somewhat depending on the pages affected, what is clear is that this impact is significant.

Why are shopping carts slow?

There are four common shopping cart performance culprits:

1. Too many pages in the checkout process

There’s a reason why companies like Amazon have made it a priority to allow one-click checkout for customers who want to hustle through the purchasing process. They know that each stage in the checkout process is an invitation for attrition.

2. Security

The checkout process must be secure, but this security can come with a performance price tag. Security is a big issue — too big to be summed up in a single paragraph — but suffice it to say that if you want to make your checkout process faster, you really need to take a deep look at how your site handles security. (It goes without saying that I wouldn’t be bringing this up if I weren’t able to assure you that Radware has you covered with our complementary security and acceleration solutions.)

Quick tip: Enable your HTTPS content to be cached by the browser, which will help checkout pages render somewhat faster. There’s a myth that HTTPS content can’t be cached, but in actuality this is controllable with response headers, just like HTTP content.

3. Too many page objects

Enabling browser caching will help with this problem, as will resource consolidation, compression, and a number of other performance best practices. Site owners should also take a close look at checkout pages and weed out extraneous images, JavaScript, and other large files. Not only do these consume unnecessary bandwidth, they’re also distracting when shoppers should be focusing on completing a single task.

4. Third-party service calls

If your site uses third-party services — such as address validation, credit card authorization, and analytics — these services need to perform quickly and reliably during checkout. This means understanding your service-level agreements (SLAs) with third-party providers and knowing what kind of monitoring and performance reporting these providers offer. You need to have full transparency into their performance so that you can make or request fixes.


In recent years, online retailers have begun to focus on accelerating their key landing pages and product pages, but many are still neglecting their checkout process. To maximize sales, every single page of a transaction — from landing page through to order confirmation page — needs to be fast. This is an excellent opportunity to make performance improvements that could make the difference between online browsers and online customers.

Tammy Everts

As a senior researcher, writer, and solution evangelist for Radware, Tammy Everts has spent years researching the technical, business, and human factor sides of web/application performance. Before joining Radware, Tammy shared her research findings through countless blog posts, presentations, case studies, whitepapers, articles, reports, and infographics for Strangeloop Networks. Tammy continues to deepen the publicly available body of web performance and UX research by regularly contributing her insights and research findings to the Radware blog, as well as the performance blog, Web Performance Today:


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