message: perf(Overlay): lazy render
diff: import { Transition } from 'vue';
  import { createNamespace, isDef, noop } from '../utils';
  import { preventDefault } from '../utils/dom/event';
  +import { useLazyRender } from '../composition/use-lazy-render';
  const [createComponent, bem] = createNamespace('overlay');
  @@ -22,7 +23,9 @@ export default createComponent({
  },
  setup(props, { slots }) {
  - return function () {
  + const lazyRender = useLazyRender(() => props.show);
  +
  + const renderOverlay = lazyRender(() => {
  const style = {
  zIndex: props.zIndex,
  ...props.customStyle,
  @@ -33,7 +36,6 @@ export default createComponent({
  }
  return (
  - <Transition name="van-fade">
  <div
  vShow={props.show}
  style={style}
  @@ -42,8 +44,9 @@ export default createComponent({
  >
  {slots.default?.()}
  </div>
  - </Transition>
  );
  - };
  + });
  +
  + return () => <Transition name="van-fade">{renderOverlay()}</Transition>;
  },
  });
  