// Know how fast your HTML Imports are
var imports = document.querySelectorAll('link[rel="import"]');
[].forEach.call(imports, function(link) {
  var entries = performance.getEntriesByName(link.href);
  console.info('=== HTML Imports perf ===');
  entries.forEach(function(e) {
    console.log(e.name, 'took', e.duration, 'ms');
  });
});