<!DOCTYPE html>
<html>
  <head>
    <title>Wait for it...</title>
  </head>
  <body>
  Try to go to another page.
  <script>
    addEventListener("StartLongLoop", function() {
      setTimeout(() => {
        const start = Date.now();
        while (Date.now() - start < 7500);
        window.dispatchEvent(new CustomEvent("LongLoopEnded"));
      });
    });
  </script>
  </body>
</html>
