Ember inspector 100% cpu

models.singer-part.js

import DS from 'ember-data';

export default DS.Model.extend({
  songPart: DS.belongsTo('song-part'),
  singer: DS.belongsTo('singer'),
});

models.singer.js

import DS from 'ember-data';

export default DS.Model.extend({
  singerParts: DS.hasMany('singer-part')
});

models.song-part.js

import DS from 'ember-data';

export default DS.Model.extend({
  song: DS.belongsTo('song'),
  singerParts: DS.hasMany('singer-part')
});

models.song.js

import DS from 'ember-data';

export default DS.Model.extend({
  songParts: DS.hasMany('song-part'),
});

router.js

import Ember from 'ember';
import config from './config/environment';

const Router = Ember.Router.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
    this.route('song', { path: ':song_id' });
});

export default Router;

routes.application.js

import Ember from 'ember';

export default Ember.Route.extend({
  init() {
    this._super(...arguments);
     
    $.mockjax({
      url: '/api/mock',
      responseText: {
        text: "someText"
      }
    });
  },
});

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({
  redirect(){
    this.replaceWith("song", {"song_id": 1});
  }
});

templates.application.hbs

{{outlet}}

templates.song.hbs

{{model.id}}
{{#each model.songParts as |songPart|}}
	{{songPart.id}}
  {{#each songPart.singerParts as |singerPart|}}
	  {{singerPart.id}}
    {{singerPart.singer.id}}
  {{/each}}
{{/each}}

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",
    "jquery-mockjax": "https://cdnjs.cloudflare.com/ajax/libs/jquery-mockjax/1.6.2/jquery.mockjax.js"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}