Performant Web Animation Eliminate the #1 cause of janky web animation: animating properties that force the browser to recalculate layout (reflow) or repaint on every frame. The browser renders in stages — layout → paint → composite . Animating , , , , , , , or re-runs layout and/or paint each frame, blocking the main thread. Animating and runs entirely on the compositor (often the GPU), skipping layout and paint, which is what makes animation smooth at 60/120fps. When to use Use when an animation stutters or drops frames, when a hover/scroll effect feels heavy, when animating size/position/s…