First, when trying to understand EF performance, we need to know what stages EF operates on in order to actually query the database server with our object query. We always must keep in mind that EF is an object model mapped to a physical model that is produced from database's metadata. When we make a query, it is made across the entity objects that are mapped to the known physical layer within the EF itself. This mapping later produces the right SQL, which is sent to the database server. This means that if a change is made against the database metadata, the known metadata in EF may become invalid and produce runtime errors.

Talking about performance, we must dive deep into SQL materialization. This knowledge of the stage list made by EF becomes critical.