Site speed, site speed, site speed. Everyone around me is sick of hearing me rant about it, probably because I’ve pushed it on every client Portent’s had since, oh, 2008.
Well, tough poo, ’cause I’m doing it again. Portent’s analytics genius, Michael Weigand, and his faithful right-hand man, Timothy Gillman, did some math based on e-commerce data from 16 sites. I then tested 500 e-commerce sites using YSlow for basic performance data.
What We Found
Here’s the breakdown of our results, plus how you can capitalize:
Still slow after all these years.
In spite of a small riot of experts who agree that faster is better, most sites are still slow. In our study, 50% of sites average load times of 5+ seconds. That’s with a standard deviation of 8 seconds (yikes) so we trimmed outliers and still got 5 seconds with a deviation of .5s.
At least get from 8 seconds to 5
The biggest and easiest value/page view jump is from 8 second to a 5 second load time. While the biggest revenue jump is between 2 seconds and 1, going from 8 to 5 seconds is easier and generates an 18% value/page view increase.
Page load time: Go from 8 to 5
But every second you shave off your site’s average page load time (without shedding page views) means an 8% improvement in page value, so keep going.
Some pages matter more than others
Hardly news, but faster checkout, login and home pages matter most. After that, load speed product category pages most impact sales. All of these pages hog high-consumer-intent traffic. Make them fast.
Page weight is not the only load time factor
Page ‘weight’ (that’s the total kilobytes transferred, images and all) is no longer the biggest factor in site load time. In our test, pages of over 4 megabytes recorded some of the fastest load times.
The reason: Many sites have streamlined their code, learned to ‘minify’ their code and to use GZIP compression. So the bigger factor, in many cases, is the server and page configuration.
If you want to speed up your site, look at:
Javascript timing
Where possible, put javascript src ‘.js’ includes at the very end of your page, defer them, or load them asynchronously. For example, if you use Google Analytics or jQuery, you’re including these scripts in your page from external files. These are ‘blocking’ calls, and your page may not appear to the user until these scripts fully load. If something goes wrong, or the script just takes a few seconds, the perceived delay can kill conversion rates.
Use deferred execution if you need to fire the javascript after the entire page loads.
Use asynchronous execution if you don’t care when the script fires.
For a great overview of deferred and asynchronous loading, see Peter Bevaloo’s explanation.
ETags and Expires headers
The top page speed issue we found was ETags and expires headers. These may sound scary, but expires headers in particular are easy to set. Your IT person or web host will know what to do.
These two settings help reduce the number of requests a browser makes to the server. They tell visiting web browsers which files to update. If set correctly, you can prevent those browsers from reloading files that rarely change, such as your logo.
Browsers will cache files with far-future expires headers and keep it cached, so the apparent load time is far shorter. And they’ll use ETags to more easily check if a file has changed.
But images are still important
Page weight may not matter as much. But image size is still a major drag on load times. Compress them, for the love of all that’s good and right in the universe. OK? Here’s one way to do it:
Run Google Page Speed for Chrome on your site. If ‘optimize images’ has an “M” or an “H”, view the Optimize Images report:
Compress Images = Happiness
If the original content is a ‘png’ image, you can replace it in one step. Click ‘See Optimized Content.’
Newly compressed image: Easy-peasy
Download the compressed images and then upload them to your server. You’ll overwrite the old, overweight image files with the new, svelte ones.
For a primer on image types and compression, see RJ’s excellent article.
Then What?
After that, things get a little more complicated. But not much. Any competent web developer or IT person can get you set up with GZIP compression, for example, or troubleshoot slow database load times. If you want to go to plaid, you can get fancier.
Research Method
For value/page view data, the team looked at just over 94 million page views across 16 e-commerce sites. The critical statistics:
We took a 90-day snapshot
Sites ranged from 61,000 to 38 million page views over the 90-day period
3 of the sites were B2B e-commerce. The rest were B2C
The sites ranged from major national fashion brands to small, niche manufacturers
For site performance data, we ran YSlow and Google PageSpeed (using the API) on 500 sites. We tested the home page and one category page on each site. Then, we did a correlation analysis, first removing outliers.
Our data sampling is strongest between 8 and 5
Potential Problems
Biggest, scariest issue with our data: There’s a weird drop in page value between 3 and 2 seconds. It’s about 9 cents. We’re looking into that, and will try to get a bigger sample to smooth the outliers
And then there’s the fact that Ian analyzed the data. I’m very aware of the Texas Sharpshooter Fallacy, and I went into this with some uh, opinions, plus a statistics background that starts with a History degree and ends in law school. Keep that in mind. However, we had the best sampling in the time increments where we’re staking our claims:
That could be good, or bad. I leave it to you to judge.
Easy Wins, Big Advantage
Compared to other digital marketing challenges, page speed is easy. And it has measurable results. But very few companies do the simple things that make a site fast. Bad news for them. Good news for you — you can gain a big competitive advantage if you just do the basics.
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