gistfile1.js

App.OldAndBustedRoute = App.Route.extend({
  /*
    Calling find from the model hook will block page rendering until (I think) the promise is fulfilled.
  */
  model: function(params) {
    return this.store.find('collection', params.collection_id);
  },

  setupController: function(controller, model) {
    controller.set('isLoading', true);

    model.get('products').then(function() {
      controller.set('isLoading', false);
    });
  }
});

App.NewHawtnessRoute = App.Route.extend({
  /*
    Returning the params will cause the page to render immediately.
    The downside is an ugly looking setupController.
    At least it increases perceived speed.
  */
  model: function(params) {
    return params;
  },

  setupController: function(controller, params) {
    controller.set('isLoading', true);

    this.store.find('collection', params.collection_id).then(function(model) {
      controller.set('model', model);
      model.get('products').then(function() {
        controller.set('isLoading', false);
      });
    });
  }
});