When you choose a specific fetch plan for loading related objects, consider the fact that this may have impact to the number and timing of requests made to the data source versus the amount of data returned by and the complexity of using a single query. Eager loading returns all related objects together with the queried objects in a single query. This means that, while there is only one connection made to the data source, a larger amount of data is returned in the initial query. Deferred or 'Lazy' loading enables you to postpone the request for related object data until that data is actually needed. This yields a less complex initial query that returns less total data. However, each successive loading of a related object makes a request to the data source and executes a query.
You may find the following topic useful:
How to: Load Object Graphs (Fetch Plans)
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