These are notes from a talk by Tim Kadlec (@tkadlec) during the HighEdWeb 2015 Technology Academy. Tim is a Technology Advocate at Akami.

  • Performance on the web is not a technical issue, it is a cultural issue.
  • Lack of Performance = Lack of Planning
  • from Beautiful Robust and Fast to Beautiful and Done on time
  • “We’re going to come back and fix it after” fails
  • If performance wasn’t a priority at the start, it won’t be a priority at the end.
  • Performance (like plumbing) is only a problem if it’s broken.
  • Performance is linked to every key performance indicator (traffic, bounce rates, revenue, conversion rates, etc.)
  • Performance Budget = A clearly defined performance goal to guide design & development
  • Four Types of Metrics:
    1. Quantity Based - metrics related to the site’s performance. Easy to understand, clear tie to design/development decisions. Not the whole picture, almost no connection to the user experience.
    2. Rule Based - adherence to specific rules. [Google PageSpeed, YSlow]. Great checklist of basic optimizations. Easy to understand. Still no connection to the user experience.
    3. Milestone Timing - Timing of a very specific moment in the course of loading the page. Easy to track and communicate. Allows for very specific metrics. Limited view of the user experience (though getting closer).
      • TTFB: when the browser receives first byte.
      • Start Render: when stuff starts to show up on the page.
      • DOMContentLoaded: execute scripts attached to the page.
      • DocumentComplete: when the document has finished executing.
      • Fully Loaded: Nothing else to load.
    4. Speed Index - a representation of the perceived load of a page, from start to finish. How quickly the majority of the content is displayed. Takes a video of the loading and then analyzes the video. Currently the best representation of the user experience. Difficult to communicate. Limited tracking options.
  • How fast is fast enough?
    • As fast as possible.
    • Study from the 1960’s around response times: if there is a 100ms delay, it feels instantaneous. If 1000ms or less keeps you within the state of flow. At 10,000ms people tend to walk away.
    • 1,000 Speed Index or less (Paul Irish)
    • But the media speed index is over 5,000 and mobile is almost 8,000.
    • This is a cultural issue with many barriers.
  • Celebrate the small victories (Lara Hogan). This helps make it part of the culture, creates sustainable change by celebrating all the small steps along the way.
  • 20% rule: “Designing and Engineering Time” Become notably faster than a competitor (20% faster). Your site and 10-12 competitors.
  • Request a WebPageTest API key. WPT-Bulk-Tester = Super cool.
  • Use the results of the 20% to set a performance budget.
  • [20% could also be just 20% faster than your site runs now]
  • You can (roughly) translate target times into file size weights
  • Designers can learn to like working within constraints.
  • perf.js gist from Tim
  • PerfBar plugin. (suggested changing the color of the bar on load)
  • Enforce: automate it!
  • Monitor.
  • What happens after load?
    • Our websites are made up of little experiences.
    • RAIL:
      • Response: 100ms = instantaneous
      • Animation: fluid 60fps (
      • Idle: if you’re going to do something, do it while the user is idle
      • Load: ready to use in 1,000ms (or your budget/goal)
        1. Pick your metrics
        2. Define your budget
        3. Enforce the budget

– KS
Web Developer at Benedictine University near Chicago