Since forever, fourth-quarter holiday sales have been the key to retail success. It was true when retail was strictly bricks-and-mortar, and it is true now when online counts for a bigger and bigger share of holiday sales. Optimizing online web performance is critical to keep and convert customers and achieve success for the holidays and the entire retail year.

Recent research from Akamai indicates that website slowdowns as small as 100 milliseconds can significantly impact revenues. Whether on desktop, tablet or mobile, consumers will not tolerate delays. Higher-than-ever expectations for mobile pose challenges.

Akamai's The State of Online Retail Performance report lays out the challenges online retailers face. But it also illuminates ideal performance benchmarks that retailers can target to make sure shoppers stick with their sites, explore their offerings, and convert into purchasers.

It takes effort to optimize your users' experience, both on the front-end and on the back-end, to achieve those benchmarks. To be successful in the fourth-quarter holiday season, that work needs to start now and continue right through the end of the year.

Study Data Correlate Web Performance and Retail Results

For the study, Akamai assembled a massive volume of user data — the equivalent of 10 billion user visits — to uncover the performance sweet spots that correlated to the lowest bounce rates, the longest user sessions, and the highest conversions.

The data show that desktop is still the online channel that delivers the highest conversions and, by inference, the most revenue. And while mobile now accounts for virtually half of online shopping, it still lags far behind in keeping and converting shoppers — just one in five transactions are completed on mobile, compared to desktop's nearly 70 percent share of completed transactions.

These numbers, however, can be deceiving when we take the consumers' cross-device journey into consideration. Many users will start their product research process on mobile devices because of their convenience. For example, users might use their mobile devices when they are on the train going to the office, and then they will complete the transaction on a desktop at work. If we look at it through this lens, a poor mobile experience will not only hurt your mobile conversion but quite possibly also damage your desktop conversion rate.

Tablets are a modest but consistent bright spot, according to the study. While they represent the smallest share of shoppers, they enjoy high conversion and low bounce rates, and consumers appear to be more tolerant of small slowdowns or performance glitches on tablets than on either desktop or mobile. These findings once again highlight the multi-device consumer path to purchase; while they may not be willing to wait on other devices, often when users are on their tablets, they are multi-screening, meaning it may increase their willingness to wait.

A One-Second Slowdown Slashes Conversion by 20 Percent

There is simply no wiggle room when it comes to website load time. Even just a 100ms delay — 1/10 of a second — reduces conversion by 2.4 percent on desktop and over 7 percent on mobile. When the delay increases to a full second, conversion plummets by more than 20 percent on desktop and mobile and almost 18 percent on tablet.

The number to aim for is the load time that delivers “peak conversion,” when the highest proportion of visitors are going to complete an action. For desktop, the magic number is 1.8 seconds to achieve a conversion rate of 12.8 percent. For mobile, a 2.7 second load time correlates to a 3.3 percent conversion rate, and on tablets, a 1.9 second load time delivers 7.2 percent conversion.

On average, the difference between a converted and non-converted session is 1.1 seconds on desktop, 0.6 seconds on mobile, and 1.0 second on tablet. All of those numbers add up to one compelling conclusion: every millisecond matters.

Read E-Commerce Secrets to Retail Holiday Success - Part 2