Wikipedia reduceds the JS initial payload to fit within a budget of 28 KB. In total, the year-long effort is saving 4.3 Terabytes a day of bandwidth on our users' page views.

This talk looks at our perception of performance, some of the issues and challenges with our current approach to designing and delivering fast experiences.
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How we design, develop and deliver our pages determines our visitor's experience.

To make sure your animations don’t cause performance issues, consider the impact of animating a given CSS property. Avoid layout recalculations and minimize repaints. Where you can, stick to changing transforms and opacity.