Intersection Observer API for Element Visibility Detection and Improved Performance
Article Summary
Pepperfry's engineering team was facing system hangs and 28% CPU usage just from scrolling. The culprit? Traditional scroll event listeners that were choking their main thread.
The Pepperfry team shares how they tackled performance issues on their image-heavy e-commerce listing pages. Their solution involved replacing scroll listeners with the Intersection Observer API for lazy loading, infinite scroll, and sticky elements.
Key Takeaways
- Reduced CPU utilization by 20% after switching to Intersection Observer
- Scroll listeners caused 28% scripting time vs 23% with IO implementation
- IO runs asynchronously, freeing main thread for user input responses
- Perfect for lazy loading, infinite scroll, and visibility tracking
- Eliminates expensive DOM queries and continuous polling overhead
Critical Insight
Switching from scroll event listeners to Intersection Observer API cut CPU usage by 20% and dramatically improved scrolling performance on Pepperfry's product pages.
