What performance advantage does using the 'Intersection Observer API' provide over traditional scroll event handlers?
The Intersection Observer API provides a significant performance advantage over traditional scroll event handlers because it runs asynchronously off the main thread. Traditional scroll event handlers fire continuously during scrolling, can cause frequent layout recalculations, and run on the main thread, potentially causing jank and degraded user experience. In contrast, Intersection Observer: 1) Operates asynchronously, not blocking the main thread, 2) Is callback-based rather than event-based, firing only when needed (when elements enter or exit the viewport or a specified element), 3) Batches multiple intersection changes together, and 4) Doesn't trigger layout calculations that are typical in scroll handlers. This makes it ideal for implementing lazy loading of images, infinite scrolling, animations based on visibility, analytics tracking, and any other functionality that depends on element visibility.