Published April 2, 20255 min readSaman Sahraei

Scroll-Driven UI Without Jank

Lenis, GSAP ScrollTrigger, and the discipline of animating only transform and opacity.

GSAPAnimationPerformance

Scroll-Driven UI Without Jank by Saman Sahraei

Scroll animations go wrong when they fight the browser. Layout thrashing, scroll jank, and main-thread clustering all come from the same mistake: animating properties that trigger reflow.

Lenis owns scroll; GSAP owns time

Lenis smooths wheel input into native scroll. GSAP reads that scroll via ScrollTrigger and drives transforms. The two systems stay in sync through a single ticker instead of competing proxies.

Animate transform and opacity only
matchMedia for reduced-motion fallbacks
Section ids that match navigation and progress rails
Kill timelines on unmount to prevent memory leaks

Motion should explain structure, not decorate it.

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