KakaoWebtoon Shares Case Study on Rendering Performance Optimization Using IntersectionObserver

KakaoWebtoon shared a case study on optimization using hardware acceleration and IntersectionObserver to resolve rendering loads caused by complex interactions and parallax effects. To reduce initial rendering delays and leverage GPU operations, they primarily used the transform: translate3d property, which is evaluated as a more flexible and efficient approach than will-change or animation properties.

In particular, they conducted tests in a Throttling environment with the CPU set to 6x slower to verify the performance of IntersectionObserver for viewport entry detection. As a result, the existing scroll event method showed unstable frames of 10~60, whereas IntersectionObserver maintained 50~60 frames, showing clear performance improvement.

This API enables precise intersection detection through root, rootMargin, and threshold options, and provides various Entry properties such as isIntersecting and intersectionRatio. KakaoWebtoon utilized this to implement Lazy Load for images and videos, blocking unnecessary resource loading and contributing to elevating overall web performance to app-level standards.