# Ember data and relationships. Performance
**URL:** https://discuss.emberjs.com/t/ember-data-and-relationships-performance/3733
**Category:** Performance
**Created:** [January 1, 2014, 9:49pm UTC](https://discuss.emberjs.com/t/ember-data-and-relationships-performance/3733 "2014-01-01T21:49:55Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@bill](https://discuss.emberjs.com/u/bill)
#### Post date: [January 1, 2014, 9:49pm UTC](https://discuss.emberjs.com/t/ember-data-and-relationships-performance/3733/1 "2014-01-01T21:49:56Z")
Hi all:
This is my second Ember Application, and the following problem has been a reoccurring theme.
I am using the Canary build of both Ember js and Ember data with query params enabled.
Say we have the following relationships:
- A has many B
- A has many C
- A has many D
- A has many E
Model B, C, D, E are huge models and resource heavy for rendering. So loading them ALL the time is not optimal.
Say if my application has a dashboard that allows for a quick glance of the state of the application, and it focuses on model A. I don’t need to display anything from B, C, D, E. So the JSON will not return the relationship ID array from the `example.com/api/a` endpoint.
And if the user clicks to the `show` route of model A then **How should I load models B, C, D, E?**
Thanks All
---
### Author:  [@gordon\_kristan](https://discuss.emberjs.com/u/gordon_kristan)
#### Post date: [January 1, 2014, 11:13pm UTC](https://discuss.emberjs.com/t/ember-data-and-relationships-performance/3733/2 "2014-01-01T23:13:27Z")
I’ve been using a very old version of Ember Data for a long time, and I _just_ updated to the latest version a few days ago. Because of this, take what I say with a grain of salt. 😄 But I believe that Ember Data only loads records/relationships lazily. So you should return the IDs for B, C, D, E along with the JSON for A, and then Ember Data should load the records for them automatically as soon as you reference them.
EDIT: Almost forgot. You must include the `async: true` option for this to work.
```auto
App.A = DS.Model.extend({
b: DS.hasMany('b', { async: true });
});
```
---
### Author:  [@bill](https://discuss.emberjs.com/u/bill)
#### Post date: [January 3, 2014, 3:47pm UTC](https://discuss.emberjs.com/t/ember-data-and-relationships-performance/3733/3 "2014-01-03T15:47:46Z")
This was the solution. Thanks @gordon_kristan!
It never occurred to me that Ember will only lazy load _iff_ the relationship is being accessed.