1.
T R A C K I N G
PA G E
S P E E D
S E R G E Y C H E R N Y S H E V

2.
S C A L A B I L I T Y & P E R F O R M A N C E
number of users
timetoload

3.
number of users
timetoload
S C A L A B I L I T Y & P E R F O R M A N C E
0

4.
S C A L A B I L I T Y & P E R F O R M A N C E
One User
timetoload
0
S1

5.
W H Y D O W E M E A S U R E S P E E D ?
• Monitor for degradations (Ops)
• Analyze code for perf issues (Devs)
• Verify improvements (Devs)
• Prioritize improvements (Business)
• Budget for WPO initiatives (Business)

6.
S TAT S
• Pinterest: -40% wait time => +15% SEO, +15% conversion (2017)
• DoubleClick: 5s vs 19s on mobile => 2x ad revenue (2016)
• Trainline: -300ms latency => +$11.5M / year revenue (2016)
• Etsy: +160Kb => +12% bounce rate (2014)
• Edmunds: -77% load time => +20% page views (2011)
• Mozilla: -2.2s => +15.4% Downloads (2010)
• Google: +400ms => -0.21% searches after experiment! (2009)
• Netflix: +GZip => -43% Traffic cost (2008)
• Amazon: +100ms => -1% revenue (2008)
• Google: +500ms => -25% searches (2006) WPOStats.com

7.
WHAT DOES MY SITE COST? WHATDOESMYSITECOST.COM
http://www.disney.com/

8.
% OF DAILY BUDGET WHATDOESMYSITECOST.COM
http://www.disney.com/

9.
http://www.slownesskills.com

10.
S Y N T H E T I C M O N I T O R I N G ,
T E S T I N G & A N A LY S I S
• From particular location
• Tester controls instrumentation
• One metric value
• Data can have lots of details for analysis

11.
R E A L U S E R M E A S U R E M E N T
• Real users (a lot of them)
• A lot of data (need to store it)
• All noise you can get, requires filtering
• Metrics are distributions
• Can correlate to business KPIs

12.
T O D AY ' S M E T R I C S
• DNS, SSL/TLS, Time To First Byte (TTFB)
• Page Load, Document Complete, Fully Loaded
• Size of DOM, Frames per Second
• First Paint, First “Contentful” or Meaningful Paint
• Above the Fold Time (AFT)
• SpeedIndex

13.
T I M E T O F I R S T PA I N T
• Shows when completely useless part is over
TTFP
3.5s

14.
A F T ( A B O V E T H E F O L D T I M E )
• When everything is finally visible
AFT
15.3s

15.
S P E E D I N D E X
• Unifies rendering progress in one number
Speed Index
8618

16.
M E A S U R E U S E R E X P E R I E N C E
• Great experience for users
• "Fast" is just a component
• Correlate what you measure
to business KPIs
• Do not measure what's easy,
measure what matters
N O T T E C H N O L O G Y

17.
I N T E R A C T I O N O N T H E W E B
1. Verify destination
2. Provide primary content
3. Allow interaction
4. Show secondary content
5. Invisible tasks
✦ Acknowledge action

18.
D E S I G N C O M P O N E N T S
1. Verify destination
2. Primary content
…

19.
E X T E N D E D M E T R I C S
• Time To First Paint (TTFP) - 3.5s
• Verify Destination - 8s
• Primary content - 11s
• ...
• Above The Fold (AFT) - 15.3s

20.
U S E R T I M I N G A P I
• Records custom JS timings on the page
• Recorded by both RUM and Synthetic tools
• Can be hard to match with user's reality
• Uses JavaScript instrumentation
https://github.com/sergeychernyshev/ux-capture

21.
H E R O E L E M E N T T I M I N G A P I
• Use elementtiming=“name” HTML attribute
• Currently recorded only by

22.
T H A N K Y O U !
sergey.chernyshev@gmail.com
@SergeyChe