1. The Fast, The Slow, and the Unconverted
https://www.flickr.com/photos/dvanzuijlekom/14579895325/
@AndyDavies, NCC Group

2. “Has it loaded yet?”
http://www.flickr.com/photos/kindofindie/4099768084

3. Response Time in Man-computer Conversational Transactions
Robert B. Miller, 1968
How we perceive response times
100ms 1s 10s
IRUK Retail Top 100 : Average 1.8s delay before page starts showing content

4. “50% more concentration when using
badly performing web sites”
Foviance
http://www.flickr.com/photos/yourdon/3366991042

5. https://www.flickr.com/photos/editor/57572350
“Stress levels comparable to watching a horror movie”
Ericsson Mobility Report 2016

6. Abandonment rate for 200+ sites / 177+ million page views over 2 weeks – Measureworks / Gomez
Abandonment increases with load time...

7. Slow sites = negative impact on brand perception
‘Normal Speed’ 0.5s added delay
Mobile Web Stress: Understanding the Neurological ImpactofPoor Performance,Tammy Everts, Radware

8. Slow experiences can lose visitors forever!

9. Conversions decrease with load time
Walmart 2012

10. Increased conversions by 10%
Shaved 1 second off median home page time
6 seconds off 98th percentile
http://www.slideshare.net/cliffcrocker/velocity-ny-how-to-measure-revenue-in-milliseconds

11. Improved load time from 1.2s to 0.5s
+28% page views / session
+21% time on site / visit
+20% conversion rate
http://blog.quanta-computing.com/etam-earns-20-of-conversion-by-optimising-its-online-store/

12. “We reduced latency by 0.3s across the funnel and
customers spent 8m a year in additional revenue”
Mark Holt, CTO, Trainline
New Relic London Summit 2016

13. wpostats.com has many more examples

14. Good performance is
fundamental to the
success of our sites

15. And we know how to make sites fast…

16. https://www.flickr.com/photos/justinjovellanos/15340862812
But we have another challenge…

17. https://www.flickr.com/photos/jamescridland/613445810
Revenue attribution Analytics
Personalisation A/B & MV testing
Advertising Value added content
Product images Critical content
We depend on Third-Party services for:

18. Third-party = Infrastructure and code
managed by someone else
Guy Podjarny / Velocity Santa Clara 2014

19. https://discuss.httparchive.org/t/what-is-the-distribution-of-1st-party-vs-3rd-party-resources/100/7
and we’re using more and more of them
0
5
10
15
20
25
30
2011 2012 2013 2014 2015
Median Number of Third Parties

20. http://requestmap.webperf.tools/render/150519_VW_8c8fbf2ecdebe417724d645f9ac3c4cf
But do we understand their impact?

21. Or the risks they bring?
https://http://www.webperformancetoday.com/2011/07/14/fourth-party-calls-third-party-content/

22. https://www.flickr.com/photos/devos/163903
With great power…
…comes great responsibility

23. https://www.flickr.com/photos/matt512/4065627169
What if a third-party includes something
that’s blocked in China?

24. Or breaks something really important?

25. https://www.flickr.com/photos/derekbruff/9759290413/
What about their impact on speed?

26. https://www.flickr.com/photos/torek/4444673930
Let’s pick an easy target

27. SpeedIndex – Measure of how quickly screen is drawn
(A lower is score better)

28. 0.00%
0.50%
1.00%
1.50%
2.00%
2.50%
Speed Index
Percentage Tests With AB
Percentage Tests Without AB
Pages that use AB or MV Testing are slower
Data from httparchive.org

29. With Optimizely Optimizely Removed
A Real-World Example

30. With Optimizely Optimizely Removed
A Real-World Example

31. With Optimizely Optimizely Removed
A Real-World Example

32. With Optimizely Optimizely Removed
A Real-World Example

33. Just adding the testing service
changes the visitor’s experience!
https://www.flickr.com/photos/therontrowbridge/2654049085

34. https://www.flickr.com/photos/87975067@N06/8048048692
Will the value of the tests be larger than the
impact on the visitor’s experience?

35. Are you brave enough to test
the impact of AB testing?

36. This is was one example, other types of
third-parties have different impacts

37. We need to balance third-party benefits
with their impact on performance
https://www.flickr.com/photos/synx508/5839490755/

38. https://www.flickr.com/photos/magickevin/3595741847
Find the third-parties we’re using

39. https://www.flickr.com/photos/jamescridland/613445810
Revenue attribution Analytics
Personalisation A/B & MV testing
Advertising Value added content
Product images Critical content
Establish the business value they bring

40. Remove the ones we don’t use anymore

41. https://www.flickr.com/photos/derekbruff/9759290413/
Measure their impact on speed

42. https://www.flickr.com/photos/editor/57572350
Use Real User Monitoring to measure visitor’s experiences

43. 0.0%
0.5%
1.0%
1.5%
2.0%
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
%ofVisitors
Page Load Time (s)
Tablet
Phone
Desktop
So we can see how we’re performing for them

44. And how it effects their behaviour
https://www.flickr.com/photos/mujitra/5232270530

45. https://www.flickr.com/photos/borkazoid/221185817
To deliver a great experience we need to be deliberate

46. @andydavies
andy.davies@nccgroup.com
http://slideshare.net/andydavies
Thank You!
https://www.flickr.com/photos/nzbuu/4093456029