Upgrading to Ember 2.3 from Ember 1 caused slow loading of the app

I am upgrading an Ember 1 project to Ember 2.3, initially all went fine. I created individual models of the classes made in Ember 1, imported required models in a particular model, if any method call was required from them. Say model X needs methods from 16 different models randomly then those 16 models were imported in X.

But by the time app is taking shape its becoming very very slow to load, at times 3-4 minutes and sometimes even more. After loading it works smoothly.

Also I am not using controllers any more as per Ember 2.3 recommendation. I converted Controllers from Ember 1 to models (classes) in Ember 2.3 (as they ll be soon deprecated as recommended by Ember.js.

Plz tell me how to use those model made out of controllers from Ember 1 so that they fuse with respective routes as controllers.

Finally, Plz let me know the reason of slow loading and last para solution.

Regards

Dn