Building a Better Web
June 19–20, 2017: Training
June 20–22, 2017: Tutorials & Conference
San Jose, CA

Perceived performance: The only kind that really matters

Eli Fitch (Social Tables)
4:25pm–5:05pm Wednesday, June 21, 2017
Performance Matters
Location: 210 AE
Secondary topics:  CSS3, Performance culture, UX optimization
Average rating: ****.
(4.94, 16 ratings)

Who is this presentation for?

  • Frontend developers and product, UX, and web designers

Prerequisite knowledge

  • Intermediate CSS and JavaScript experience
  • Familiarity with event listeners and CSS animations

What you'll learn

  • Learn a whole new way to think about how users interact with your work
  • Learn how to apply psychology to evaluate when it makes sense to optimize for perceived performance over objective speed and some basic (and not-so-basic) ways to “trick” users into thinking that your projects are faster than they actually are


We all want our projects to be fast. We agonize over JavaScript bundle sizing, our chosen CSS preprocessor’s impact on stylesheet bloat, caching schemes, and more as we head down the performance rabbit hole. But here’s the rub: doggedly chasing kilobytes isn’t an efficient way to improve your project’s performance if users aren’t be able tell the difference. At the end of the day, perceived performance—what users feel and experience while using your app—is what truly matters.

This isn’t easy. Humans are imprecise beings, and how we perceive the world around us is fraught with fascinating quirks. Improving perceived performance is likewise an incredibly challenging prospect. If people don’t perceive time accurately, how can you possibly hope to build to meet this nebulous standard?

In order to make experiences that feel satisfying, you need to understand the basic psychology behind how humans perceive time in the world around them. This opens the door to a universe of possibilities and a deeper connection with the users we all serve.

Eli Fitch discusses the psychological basics of how people sense time and explains how to use this understanding to create experiences that feel fast, tactile, and satisfying.

Topics include:

  • When it makes sense to focus on perceived performance over outright speed
  • How to turn the difference between active and passive mental states to our advantage
  • When to choose between a progress bar instead of a spinner
  • How to cleverly craft animations to make loading seem faster
  • When to use unconventional event listeners to increase perceived speed
  • Predictive design: How to predict future behavior and load what’s necessary ahead of time
Photo of Eli Fitch

Eli Fitch

Social Tables

Eli Fitch is a frontend developer with a passion for web performance, animation, and all things 3D. He leads a team of amazing engineers making a WebGL event diagramming app at Social Tables, a startup in his hometown of Washington, DC. He also organizes the DC CodePen meetup and dabbles in design, 3D art, and game development. When not in front of a computer, he restores his perpetually broken stable of 1970s motorcycles and attempts to keep his historic row house from collapsing in on itself like a dying star.

Comments on this page are now closed.


Picture of Eli Fitch
Eli Fitch | TECH LEAD
07/25/2017 1:28am PDT

It’s also available alongside all the other talks on O’Reilly’s safari platform ✌️

Picture of Eli Fitch
Eli Fitch | TECH LEAD
07/25/2017 1:27am PDT

@Jaroslaw Batorski Video is available here

07/17/2017 1:46am PDT

Will the video of this presentation be made available?