route loading jank

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  queryParams: ['greeting'],
  greeting: 'Hallo'
});

routes.application.js

import Ember from 'ember';

const { run: { later }, RSVP: { Promise } } = Ember;

export default Ember.Route.extend({
  queryParams: {
  	greeting: { refreshModel: true }
  },
  model() {
  	return new Promise((resolve, reject) => {
    	later(null, resolve, 2000);
    }); 
  }
});

templates.application-loading.hbs

<h1>L O A D I N G</h1>

templates.application.hbs

<h1>{{greeting}}, welcome to my app!</h1>
<br>
<br>
{{outlet}}
<br>
<br>

Change greeting: 

<input type="text" value={{greeting}} oninput={{action (mut greeting) value="target.value" placeholder="Change greeting"}}>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}