7–9 November 2016: Conference & Tutorials
9–10 November 2016: Training
Amsterdam, The Netherlands

Balancing performance best practices and resilient engineering on a large scale

Cynthia Mai (Amazon)
14:40–15:20 Tuesday, 8/11/2016
UX performance Resilience engineering, UX optimization Auditorium (Ground + Balcony) Audience level: Intermediate
Average rating: ***..
(3.80, 30 ratings)

Prerequisite knowledge

  • A basic understanding of performance best practices

What you'll learn

  • Explore case studies of resilience FE engineering from AmazonUI, a centralized frontend library used on the majority of Amazon.com traffic


Many performance best practices just do not work out of the box when it comes to large-scale infrastructure or development environments. As engineers, we need to understand the use cases and architecture we’re dealing with and adapt best practices to create the best perceived user experience. Cynthia Mai shares several real-world examples from Amazon’s large-scale (billions of page views per week), distributed development community (thousands of engineers), including:

  • Preloading: Years ago, Amazon started using preloading techniques and saw big performance wins across pages on Amazon.com; however, a recent update to its preloading logic to include new browsers did not yield similar results (some regression indeed). Cynthia outlines the lessons learned and explains how Amazon derived the next step in optimizing preloading.
  • One-for-all responsive design: The “one DOM/CSS for all responsive design” concept does not work at a large scale. For instance, the use of media query adds unwanted maintenance costs across hundreds of teams. It’s also not accurate enough to cover the large variety of mobile devices, and serving unused PC and table CSS to mobile not only wastes data served down the wire but also slows down page performance. Cynthia discusses how Amazon evolved from one-for-all responsive design to RESS (responsive design with server-side components) and performance wins.

Cynthia concludes with a look at how Amazon is able to run all these site-wide changes with only a single team, in one single codebase, without breaking anything or making backward-incompatible changes, thanks to the resilient design of the AmazonUI frontend platform.

Photo of Cynthia Mai

Cynthia Mai


Cynthia Mai is a San Francisco-based software engineer at Amazon, where she works on AmazonUI, a frontend framework that is used on the wide majority of Amazon.com pages across desktop, mobile, and tablet.

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Picture of André Morrow
André Morrow
16/11/2016 23:31 CET

I apologize but the slide for this session will not be available.

Picture of Peter Brouwers
Peter Brouwers
10/11/2016 11:12 CET

Will the slides be shared over here?