Site-Speed That Sticks

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Harry Roberts

November 14, 2024
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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 dasard 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