chromium/third_party/blink/perf_tests/layout/flexbox-hittest.html

<!DOCTYPE html>
<script src="../resources/runner.js"></script>
<style>
  div {
    display: flex;
    border: 1px solid grey;
    align-items: center;
  }

  p {
    margin: 0.2em;
    font-family: Ahem;
  }
</style>
<div>
  <p>1</p>
  <div>
    <p>2</p>
    <div>
      <p>3</p>
      <div>
        <p>4</p>
        <div>
          <p>5</p>
          <div>
            <p>6</p>
            <div>
              <p>7</p>
              <div>
                <p>8</p>
                <div>
                  <p>9</p>
                  <div>
                    <p>10</p>
                    <div>
                      <p>11</p>
                      <div>
                        <p>12</p>
                      </div>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>
<script>
function runTest() {
  // 320, 30 is where the "12" is in Ahem font.
  document.elementsFromPoint(320, 30);
}

PerfTestRunner.measureRunsPerSecond({
  description: "Measure elementsFromPoint from a deeply nested flexbox.",
  run: runTest,
});
</script>