chromium/third_party/blink/perf_tests/layout/hittest-block-children.html

<!DOCTYPE html>
<title>Hit-testing block children</title>
<script src="../resources/runner.js"></script>
<body>
<div id="container"></div>
<script>
let y = 100;

function createTree(container) {
  for (let i = 0; i < 20000; ++i) {
    const div = document.createElement('div');
    div.textContent = i;
    container.appendChild(div);
  }
}

function setup() {
  container.textContent = '';
  createTree(container);
}

function test() {
  for (let i = 0; i < 10; ++i) {
  document.elementFromPoint(100, y);
  ++y;
  }
}

function run() {
  PerfTestRunner.measureTime({
    description: `Measures performance of hit-testing block children.`,
    run: test
  });
}

setup();
run();
</script>
</body>