DelayLoading is true/false(default) in Linq to Sql?

Yes, linq to sql uses lazy loading/delayloading --->give good performance by default with the help of

DelayLoading =False(default)--->along with the Column name

like
 ProductName  Delay Loaded=false

then ProductName Delay Loaded=true------> this ProductName is not loaded.

so what is advantage?

Note : If we set Delay Loaded =true for Primay key column ------>Even also which will loaded.