Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Site-Speed That Sticks

Avatar for Harry Roberts Harry Roberts
November 14, 2024
Technology
1.2k
13

Site-Speed That Sticks

Avatar for Harry Roberts

Harry Roberts

November 14, 2024

More Decks by Harry Roberts

See All by Harry Roberts
Build for the Web, Build on the Web, Build With the Web
Avatar for Harry Roberts csswizardry
0
470
How to Think Like a Performance Engineer
Avatar for Harry Roberts csswizardry
28
2.7k
cache rules everything
Avatar for Harry Roberts csswizardry
5
3.8k
My Website Is Slow!
 Where Do I Start?
Avatar for Harry Roberts csswizardry
5
590
Optimising Largest Contentful Paint
Avatar for Harry Roberts csswizardry
37
3.8k
Get Your Head Straight
Avatar for Harry Roberts csswizardry
15
21k
From Milliseconds
 to Millions: A Look at the Numbers Powering Web Performance
Avatar for Harry Roberts csswizardry
1
2.7k
More Than You Ever Wanted to Know About Resource Hints
Avatar for Harry Roberts csswizardry
6
10k
It’s My (Third) Party, and I’ll Cry if I Want To
Avatar for Harry Roberts csswizardry
13
5.9k

Other Decks in Technology

See All in Technology
“ID沼入口” - 基本とセキュリティから始める、考え続けるためのID管理技術勉強会 告知&イントロ
Avatar for ritou ritou
0
380
Amazon EVS で VCF 9.0 / 9.1 のサポート開始まとめ
Avatar for mtoyoda mtoyoda
0
190
AIをフル活用してオンコール機能のプロトタイプを2日で作った話 / Building an AI-Powered On-Call Prototype in Just Two Days
Avatar for Narimichi Takamura nari_ex
0
180
なぜ私たちのSREプラクティスはなかなか機能しないのか 〜システムより先に組織を見る〜 / Why our SRE practices aren't really working
Avatar for VTRyo vtryo
0
210
#エンジニアBooks 30分でわかる
「技術記事を書く技術」 / engineer-books 2026-06-30
Avatar for Junichi Ito jnchito
1
180
ループエンジニアリングでE2Eテストを実践
Avatar for Noriyuki TAKEI noriyukitakei
0
260
SRE歴2ヶ月でも開発6年の知見を活かして、チームで止まっていた環境改善を前に進めた話
Avatar for a_ono a_ono
0
200
【FinOps】データドリブンな意思決定を目指して
Avatar for kaita z63d
3
600
SRE依存からの脱却 運用を開 発チームへ移す、 フルサイ クル開 発体制の実践
Avatar for joe joooee0000
0
160
RAGの精度向上とエージェント活用
Avatar for KintoTech_Dev kintotechdev
2
130
MySQL & MySQL HeatWave Report - June 2026
Avatar for Olivier DASINI freshdaz
0
310
どうして今サーバーサイドKotlinを選択したのか
Avatar for Nealle nealle
0
190

Featured

See All Featured
30 Presentation Tips
Avatar for Ian Lurie portentint
PRO
1
340
Balancing Empowerment & Direction
Avatar for Lara Hogan lara
6
1.2k
Practical Tips for Bootstrapping Information Extraction Pipelines
Avatar for Matthew Honnibal honnibal
25
2k
What the history of the web can teach us about the future of AI
Avatar for Ines Montani inesmontani
PRO
1
630
Ruling the World: When Life Gets Gamed
Avatar for Sebastian Deterding codingconduct
0
270
Exploring the relationship between traditional SERPs and Gen AI search
Avatar for Ray Grieselhuber raygrieselhuber
PRO
2
4.1k
Accessibility Awareness
Avatar for Sarah Abderemane sabderemane
1
150
DevOps and Value Stream Thinking: Enabling flow, efficiency and business value
Avatar for Helen Beal helenjbeal
1
250
Dealing with People You Can't Stand - Big Design 2015
Avatar for Cassini Nazir cassininazir
367
27k
Building Better People: How to give real-time feedback that sticks.
Avatar for Will Jessup wjessup
370
20k
Navigating Weather and Climate Data
Avatar for Ryan Abernathey rabernat
0
270
A better future with KSS
Avatar for Kyle Neath kneath
240
18k

Transcript

  1. site-speed that sticks

  2. None

  3. hi, i’m harry

  4. None

  5. five key topics

  6. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  7. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  8. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  9. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  10. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  11. 1. metrics 2. localhost 3. backstops 4. monitoring 5. playbook

  12. metrics

  13. not all metrics are born equal

  14. different metrics for different people on different occasions with different

    levels of disclosure

  15. kpis, enablers, predictors

  16. kpis

  17. definition + target

  18. what are we working toward?

  19. of interest to the business

  20. core web vitals

  21. ‘which number on which dashboard of which service?’

  22. “We want a one-second improvement in Largest Contentful Paint.” —

    My Client
  23. None
  24. None
  25. None

  26. enablers

  27. metrics that directly influence kpis

  28. of interest to engineering teams

  29. ttfb, input delay

  30. predictors

  31. signals of good/bad performance

  32. highly quantitative

  33. of interest to engineers

  34. bundle size, long tasks, blocking css

  35. great for root-causing and reverse engineering

  36. localhost

  37. localhost is: seldom live-like, pretty dang fast, un-bundled

  38. know your tools inside out

  39. None
  40. None

  41. csswz.it/perfnow25

  42. one weird trick…

  43. None

  44. // plugins/delay.server.ts export default defineNuxtPlugin(async () => { await new

    Promise(resolve => setTimeout(resolve, 900)) })
  45. None
  46. None

  47. <head> <link rel=stylesheet href=https://slowfil.es/file?type=css&delay=800> </head>

  48. core web vitals are too big for localhost

  49. if you’re working locally, measure locally

  50. bare-metal metrics

  51. None
  52. None

  53. 1

  54. 1 2

  55. 1 2 3

  56. 1 2 3

  57. None
  58. None

  59. 1

  60. 1 2

  61. 1 2 3

  62. 1 2 3

  63. external: 1842ms inlined: 1250ms

  64. None

  65. these are very private metrics

  66. backstops

  67. …and budgets

  68. what is the worst possible performance we will accept?

  69. set it to the worst reading in the last release

    cycle
  70. None

  71. this is where synthetic testing comes into it

  72. synthetic testing; real user monitoring

  73. when to fail a release

  74. None

  75. predictors as tripwires

  76. None

  77. budgets versus targets

  78. budgets are backstops; targets are ambitions

  79. target == kpi

  80. None

  81. monitoring

  82. the m in rum stands for monitoring

  83. “Insanity is doing the same thing over and over again

    and expecting different results.” — Rita Mae Brown
  84. None

  85. 🎉

  86. ?

  87. None
  88. None
  89. None
  90. None

  91. it’s the exact same file

  92. None

  93. you’re monitoring variation in tests

  94. None

  95. only alert on your kpis

  96. None
  97. None

  98. 0.9952409649

  99. None
  100. None

  101. always follow the numbers

  102. playbook

  103. “Fighting regressions took priority over optimizations […]” — Michelle Vu,

    Pinterest
  104. None

  105. it’s all for nothing if you don’t have a plan

  106. response = f(severity, duration)

  107. severity

  108. acceptable: <10%

  109. moderate: 10–25%

  110. severe: 25–50%

  111. critical: >50%

  112. duration

  113. temporary: 24–48hr

  114. sustained: >48hr

  115. long-term: >1 release cycle

  116. unresolved: many release cycles

  117. a kpi regression of over 10% for one week requires

    remediation in the next sprint

  118. a kpi regression of over 100% for one hour requires

    rollback immediately

  119. a kpi regression of over 25% for one day requires

    remediation in the current sprint

  120. an enabler regression of over any% for any time needs

    the team’s attention over the next sprint

  121. a predictor regression of over any% for any time needs

    my attention over the next sprint

  122. you need a framework to fill in these blanks

  123. early triage

  124. who, what, when, where, and why?

  125. what?

  126. what has regressed?

  127. when?

  128. when did it start? is it still like that?

  129. where?

  130. is it a business-critical part of the site?

  131. who?

  132. who owns the problem?

  133. why?

  134. can you conduct early triage?

  135. None
  136. None
  137. None
  138. None
  139. None
  140. None

  141. key takeaways

  142. increase confidence

  143. use the right tool for the right job

  144. have a plan of attack

  145. agree; commit

  146. thank you

  147. harry.is/for-hire