The Performance Beacon

The web performance, analytics, and optimization blog

Metrics, metrics everywhere (but where the heck do you start?)

I just had the privilege of speaking with Cliff Crocker at Velocity Santa Clara. Our talk centered around web performance metrics — what they are, what they mean, how to use them, and how to find the right one for your purposes.

It was a 90-minute talk, so we covered a huge swath of ground. Based on people’s reactions on Twitter, these were a few of the slides and takeaways that resonated most. (I’ve also embedded our slide deck at the bottom of this post, if you’d like to check out the entire thing.)

First, a hat tip for Mike Loukides at O’Reilly for this awesome tweet, which he pushed out earlier today and which we couldn’t resist kickstarting our talk with:




Cliff talked about the fact that everyone wants a single unicorn metric that magically sums up the user experience, business value, and numbers that devops cares about. Surprise! There isn’t one. There are at least twenty.



Stats around user expectations are always well received. I really like the findings from this Forrester/Akamai survey, which found that almost half of users expect pages to load in 2 seconds or less.



I love this next graph, created by OpenSignal, which does an amazingly effective (and really pretty) job of illustrating the state of mobile device fragmentation. Looking at their own user data, they found that visitors coming to their site used almost 19,000 distinct devices.



Performance case studies from big retailers are always a hot ticket. This is a great one from Walmart. They looked at their RUM data and found that every one second of improvement correlated to a 2% increase in conversions.



The next two slides demonstrate how performance is felt differently on different pages. When “browse” pages slow down, conversions drop by up to 50%, but when “checkout” pages slow down, the impact isn’t nearly as dramatic.




At the end of the day, though, the best way to understand the potential impact of performance on your business is by looking at your own data. If you’re using a real-user monitoring solution, then you should be able to generate a histogram like the one below. It shows the distribution of traffic in terms of load time and conversion rate, and it lets you see at a glance the impact of one second of performance gains and losses on conversions. (In this case, the difference between pages that took 2.5 seconds to load versus pages that took 3.5 seconds was an 8.3% decrease in visitors that converted to customers. That’s a really significant number.)



And now here’s the deck in its entirety. As always, if you have any questions or feedback, please let me know!

What else to look for at Velocity

This is only day one of this three-day conference. Here are my picks for talks for days two and three. 

SOASTA is everywhere at Velocity this year, including keynotes, Ignite talks, parties, assorted talks, and of course at our booth (#801). Here’s a detailed roundup of where to find us.



Tammy Everts

About the Author

Tammy Everts

Tammy has spent the past two decades obsessed with the many factors that go into creating the best possible user experience. As senior researcher and evangelist at SOASTA, she explores the intersection between web performance, UX, and business metrics. Tammy is a frequent speaker at events including IRCE, Summit, Velocity, and Smashing Conference. She is the author of 'Time Is Money: The Business Value of Web Performance' (O'Reilly, 2016).

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