• 1M+ request per second
  • dedicated performance team

Regression protection

  • perf environment to run automation integration tests (100 times)
  • calculate 90th percentile of Pinner Wait Time (PWT)
  • binary search (git bisect) to detect which commit introduced the regression


  • create a <LazyLoader /> component
  • with http2 bundling is still optimal
  • img sprite for fold images would help
  • <link as="script">

Perf Timings


  • RUM (Real User Metrics)
  • Long Tasks > 50ms


Kimberly Munoz (Slack)

semantic HTML for focus management (tab)

  • focus on the DOM order instead of using JS
  • use <button> & <select> instead of building your custom with <div>
  • use modular CSS like CFPB modular framework
  • use html tags like nav, main, head, and aside
  • w3c wai-aria-practices

MarcySutton (Deque Systems)

Jem @jemyoung (Netflix)

  • buffer with generator + while(true) for paralellizing http requests but start serving them as soon as the first request is complete.

@linclark @codecartoons (Mozilla)

Parallelize as much as possible to be quicker

  • webworkers
  • shared array buffers
  • WebAssembly + React

PWA - slides

  • cost of loading
  • The Web App Manifest
  • The Offline Cookbook
  • The PRPL Pattern
  • eliminate unused code
  • traced svg (sharp) from Gatsby
  • lazyload img -> use mini versions of img so it looks blurry as a placeholder
  • uglify.js to remove unused code
  • webpack tree shaking
  • webpack bundle analyzer
  • npm sw-precache and sw-toolbox

Simon Hearne

sitespect for ABTest

timinig-Allow-Origin is required for Resource Timing

third-party-cpu-abuser 3rd party vendor uses a lot of CPU

webpagetest querystring data=true returns json



Akamai mPulse

CSP report-only to analyze third party

CSP strict dynamic


github mikewest

perfplanet service workers


proxy third party thorough your CDN

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