Passive Event Listeners is a way to improve the scroll performance by unblocking scrolling on touch and wheel event listeners, so that scrolling happens immediately while the events are processed by javascript. alexclarke@ proposed that we should treat all the touchstart and first touchmove event listeners as passive while there’s an active fling animation.
Docs: https://developers.google.com/web/updates/2017/01/scrolling-intervention https://docs.google.com/document/d/10O_wMEpKgnhCfEQ8L3JckEKvkcclwEwCLtL0nSl7usA/ https://docs.google.com/document/d/1jXaK9JcqpZtiNMoXvmgJ6sZ6K04wCO1VKIqvJeFM8wI/