If you want your site to succeed, you need to deliver a consistently fast user experience. But how do you quantify "fast"? And how do you track speed across millions and billions of user visits? When we think about measuring web performance, it’s easy to fall into an abyss of metrics. TCP connection, TTFB, start render, PageSpeed and YSlow scores. Which ones should we care about? In this talk, I share my 10-year quest in search of a unicorn metric for measuring user engagement and web performance.

1. Performance
is about people,
not metrics
@tameverts
#wds17

4. @tameverts
CXO • SpeedCurve
WPOstats.com

7. Why care?

8. “Oh… pity the hyper-impatient web
generation. Such busy lives with so
many important things to do — like post
the latest drivel onto their Facebook
pages or download the YouTube viral
video of the day. Oops, sorry — of the
minute.”
Reader comment
“For Impatient Web Users, an Eye Blink Is Too Long to Wait”
The New York Times

9. The average web user believes they waste
two days a year waiting for pages to load.

10. “Web stress”
When apps or sites are slow,
we have to concentrate
up to 50% harder to stay on task
CA Technologies, 2011

13. “Phone rage”: How people react to slow sites
Tealeaf / Harris Interactive, 2011

15. Slow websites (and apps) suck
for your visitors

16. Slow websites (and apps) suck
for your business

18. Every 1 second of load time improvement
equaled a 2% conversion rate increase for
Walmart
Staples shaved 1 second from median load
time, improved conversion rate by 10%
Fanatics cut median load times by 2 seconds,
almost doubled mobile conversions

19. WPOstats.com

20. The impact of HTML delays on mobile business metrics, Strangeloop, 2011

22. fast slow
Mobile web stress: The impact of network speed on emotional engagement and brand perception, Radware, 2013

23. Slow websites (and apps) suck

24. Define “slow”

25. Define “suck”

26. “The real thing we are after is
to create a user experience that
people love and they feel is fast…
and so we might be front-end
engineers, we might be dev,
we might be ops, but what we really
are is perception brokers.”
Steve Souders

27. How do we measure
perception… at scale?

28. TTFB DNS TCP Start render
DOM loading DOM ready Page load Fully loaded
TTI Resource timing Requests Bytes in
Speed Index PageSpeed Navigation timing DOM elements
DOM size Visually complete TTFP TTFMP

30. Load Time
the time from the start of the initial navigation
until the beginning of the window load event

31. Start Render
the time from the start of the initial navigation
until the first non-white content is painted to the
browser display

32. Speed Index
when visual content (e.g., images and video)
renders within the viewport.

33. Visually Complete
first time when visual progress reaches 100%

34. First Meaningful Paint (TTFMP)
Time to Interact (TTI)

35. We need better metrics for
measuring user experience

36. Correlates to what users
actually see in the browser
Recognizes that not all pixels
and page elements are equal
Allows us to customize what
we measure on specific pages
Is easy to use and accessible
right out of the box

39. Custom metrics FTW
Measure performance
with high-precision timestamps
https://www.w3.org/TR/user-timing/
https://speedcurve.com/blog/user-timing-and-custom-metrics/

40. How long does it
take to display the
main product image
on my site?

41. Correlates to what users
actually see in the browser
Recognizes that not all pixels
and page elements are equal
Allows us to customize what
we measure on specific pages
Is easy to use and accessible
right out of the box

44. Hero Times
H1
Largest image
Largest background image
Hero element timing
https://speedcurve.com/blog/web-performance-monitoring-hero-times/

48. https://speedcurve.com/blog/web-
performance-monitoring-hero-times/

49. Remember this…

51. 65% of seniors use the internet.
Users aged 65 and older
are 43% slower at using websites
than users aged 21-55.
Nielsen Norman Group, 2013

52. Between the ages
of 25 and 60,
our ability to use the web
declines by 0.8% a year

54. Takeaways

55. 1. Performance is user experience.
2. There is no unicorn metric.
3. You can’t understand what you don’t measure.
4. You can’t measure what you don’t understand.
5. Performance is a team effort.
6. Even small changes can make a big
difference.

56. Thanks!
@tameverts
tammy@speedcurve.com