angular: Script blocking app for some seconds ?

I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead see https://github.com/angular/angular/blob/master/CONTRIBUTING.md#question

Current behavior

I have an angular which i am loading via an iframe . The angular app is hanging the whole web browser for about 3 seconds while loading .

I am loading this iframe on window.onload I am only getting this issue in chrome.

What have i debugged:

1. I have seen the sources tab in devtools which show that there is one file which has no domain is causing problem which loading .
2. I opened this file and the code seems like this

(function(define, require, requireNative, requireAsync, exports, console, privates, apiBridge, bindingUtil, getInternalApi,$Array, $Function, $JSON, $Object, $RegExp, $String, $Error) {'use strict';// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Custom binding for the app API.

var appNatives = requireNative('app');
var process = requireNative('process');
var extensionId = process.GetExtensionId();
var logActivity = requireNative('activityLogger');

function wrapForLogging(fun) {
  if (!extensionId)
    return fun;  // nothing interesting to log without an extension

  return function() {
    // TODO(ataly): We need to make sure we use the right prototype for
    // fun.apply. Array slice can either be rewritten or similarly defined.
    logActivity.LogAPICall(extensionId, "app." + fun.name,
        $Array.slice(arguments));
    return $Function.apply(fun, this, arguments);
  };
}

// This becomes chrome.app
var app = {
  getIsInstalled: wrapForLogging(appNatives.GetIsInstalled),
  getDetails: wrapForLogging(appNatives.GetDetails),
  runningState: wrapForLogging(appNatives.GetRunningState)
};

// Tricky; "getIsInstalled" is actually exposed as the getter "isInstalled",
// but we don't have a way to express this in the schema JSON (nor is it
// worth it for this one special case).
//
// So, define it manually, and let the getIsInstalled function act as its
// documentation.
var isInstalled = wrapForLogging(appNatives.GetIsInstalled);
$Object.defineProperty(
    app, 'isInstalled',
    {
      __proto__: null,
      configurable: true,
      enumerable: true,
      get: function() { return isInstalled(); },
    });

// Called by app_bindings.cc.
function onInstallStateResponse(state, callbackId) {
  var callback = callbacks[callbackId];
  delete callbacks[callbackId];
  if (typeof callback == 'function') {
    try {
      callback(state);
    } catch (e) {
      console.error('Exception in chrome.app.installState response handler: ' +
                    e.stack);
    }
  }
}

// TODO(kalman): move this stuff to its own custom bindings.
var callbacks = { __proto__: null };
var nextCallbackId = 1;

function getInstallState(callback) {
  var callbackId = nextCallbackId++;
  callbacks[callbackId] = callback;
  appNatives.GetInstallState(callbackId);
}

$Object.defineProperty(
    app, 'installState',
    {
      __proto__: null,
      configurable: true,
      enumerable: true,
      value: wrapForLogging(getInstallState),
      writable: true,
    });

exports.$set('binding', app);
exports.$set('onInstallStateResponse', onInstallStateResponse);

})

Expected behavior

Minimal reproduction of the problem with instructions

What is the motivation / use case for changing the behavior?

Environment

Angular version: 
ng -v
Angular CLI: 1.6.6
Node: 9.4.0
OS: linux x64
Angular: 4.4.6
... animations, common, compiler, compiler-cli, core, forms
... http, platform-browser, platform-browser-dynamic, router
... tsc-wrapped

@angular/cdk: 2.0.0-beta.8
@angular/cli: 1.6.6
@angular/material: 2.0.0-beta.8
@angular-devkit/build-optimizer: 0.0.42
@angular-devkit/core: 0.0.29
@angular-devkit/schematics: 0.0.52
@ngtools/json-schema: 1.1.0
@ngtools/webpack: 1.9.6
@schematics/angular: 0.1.17
typescript: 2.2.2
webpack: 3.10.0


Browser:
- [x] Chrome (desktop) version XX
- [x] Chrome (Android) version XX
- [x] Chrome (iOS) version XX
- [ ] Firefox version XX
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX
 
For Tooling issues:
- Node version: XX  
- Platform:  
node -v = v9.4.0
npm -v = 5.6.0

Others: