GoKawiilTransitions.dev debugs animation lag by moving mask work off the paint path
The Transitions.dev team traced choppy UI animations to mask-position changes that force browsers to repaint an element each frame, which in turn re-triggers an entire filter chain on the CPU. Rather than tweak the blur radius, they replaced the animated mask with a solid-colored curtain that slides via a transform, a property browsers can composite instead of repaint.