I've run into a bit of a performance problem. I got the following database model.
![Model](https://i.stack.imgur.com/1c94s.png)

I wish to select all entries in Entity2 that doesn't have a foreign key in Entity1, in other words the navigation property must be null.

I've come up with the following LINQ query `context.Entity2Set.Where(x => x.Entity1 == null);` and it works, however it's slow. So I was wondering if there was a better (faster) way (other then indexing) to select the entries.

In the end I want to select the entries from Entity4, so performance is an issue.