Gsap Performance

1---2name: gsap-performance3description: Official GSAP skill for performance — prefer transforms, avoid layout thrashing, will-change, batching. Use when optimizing GSAP animations, reducing jank, or when the user asks about animation performance, FPS, or smooth 60fps.4license: MIT5---6 7# GSAP Performance8 9## When to Use This Skill10 11Apply when optimizing GSAP animations for smooth 60fps, reducing layout/paint cost, or when the user asks about performance, jank, or best practices for fast animations.12 13**Related skills:** Build animations with **gsap-core** (transforms, autoAlpha) and **gsap-timeline**; for ScrollTrigger performance see **gsap-scrolltrigger**.14 15## Prefer Transform and Opacity16 17Animating **transform** (`x`, `y`, `scaleX`, `scaleY`, `rotation`, `rotationX`, `rotationY`, `skewX`, `skewY`) and **opacity** keeps work on the compositor and avoids layout and most paint. Avoid animating layout-heavy properties when a transform can achieve the same effect.18 19- ✅ Prefer: **x**, **y**, **scale**, **rotation**, **opacity**.20- ❌ Avoid when possible: **width**, **height**, **top**, **left**, **margin**, **padding** (they trigger layout and can cause jank).21 22GSAP’s **x** and **y** use transforms (translate) by default; use them instead of **left**/**top** for movement.23 24## will-change25 26Use **will-change** in CSS on elements that will animate. It hints the browser to promote the layer.27 28```css29will-change: transform;30```31 32## Batch Reads and Writes33 34GSAP batches updates internally. When mixing GSAP with direct DOM reads/writes or layout-dependent code, avoid interleaving reads and writes in a way that causes repeated layout thrashing. Prefer doing all reads first, then all writes (or let GSAP handle the writes in one go).35 36## Many Elements (Stagger, Lists)37 38- Use **stagger** instead of many separate tweens with manual delays when the animation is the same; it’s more efficient.39- For long lists, consider **virtualization** or animating only visible items; avoid creating hundreds of simultaneous tweens if it causes jank.40- Reuse timelines where possible; avoid creating new timelines every frame.41 42## Frequently updated properties (e.g. mouse followers)43 44Prefer **gsap.quickTo()** for properties that are updated often (e.g. mouse-follower x/y). It reuses a single tween instead of creating new tweens on each update. 45 46```javascript47let xTo = gsap.quickTo("#id", "x", { duration: 0.4, ease: "power3" }),48    yTo = gsap.quickTo("#id", "y", { duration: 0.4, ease: "power3" });49 50document.querySelector("#container").addEventListener("mousemove", (e) => {51  xTo(e.pageX);52  yTo(e.pageY);53});54```55 56## ScrollTrigger and Performance57 58- **pin: true** promotes the pinned element; pin only what’s needed.59- **scrub** with a small value (e.g. `scrub: 1`) can reduce work during scroll; test on low-end devices.60- Call **ScrollTrigger.refresh()** only when layout actually changes (e.g. after content load), not on every resize; debounce when possible.61 62## Reduce Simultaneous Work63 64- Pause or kill off-screen or inactive animations when they’re not visible (e.g. when the user navigates away).65- Avoid animating huge numbers of properties on many elements at once; simplify or sequence if needed.66 67## Best practices68 69- ✅ Animate **transform** and **opacity**; use **will-change** in CSS only on elements that animate.70- ✅ Use **stagger** instead of many separate tweens with manual delays when the animation is the same.71- ✅ Use **gsap.quickTo()** for frequently updated properties (e.g. mouse followers).72- ✅ Clean up or kill off-screen animations; call **ScrollTrigger.refresh()** when layout changes, debounced when possible.73 74## Do Not75 76- ❌ Animate **width**/ **height**/ **top**/ **left** for movement when **x**/ **y**/ **scale** can achieve the same look.77- ❌ Set **will-change** or **force3D** on every element “just in case”; use for elements that are actually animating.78- ❌ Create hundreds of overlapping tweens or ScrollTriggers without testing on low-end devices.79- ❌ Ignore cleanup; stray tweens and ScrollTriggers keep running and can hurt performance and correctness.