The Secret Life of JavaScript: The Scroll

Unblocking the Compositor: How to Fix Mobile Scroll Lag Frozen Timothy swiped his thumb across his Android screen. The parallax dashboard he had spent all morning building lurched forward, froze for a fraction of a second, and then snapped to a new position. It felt like dragging a brick through mud. He dropped the phone on his desk and glared at his desktop monitor, where the exact same code was running flawlessly in his dark-themed IDE. "I don't understand," Timothy muttered. "I batched my DOM reads and writes. I used requestAnimationFrame . The Main Thread is completely optimized, but the mobile experience is completely unusable." Margaret leaned against his cubicle wall, her signature dark roast coffee in hand. She picked up his phone, swiped the screen, and watched the UI stutter. "Your Main Thread might be optimized, but you are still forcing the browser to use it for something it shouldn't," Margaret said. She set the phone down and pointed to a single line of code on his screen