How to update a lot of data with good performance

See more:

EF5.0

entity-framework

EF6.0

I'm using Entity Framework 4.1
When i update entity (has child table with 50 data), it will be long time
Cause of EF will send 50 delete query and 50 insert query to child table
the example code is below :

var existingEntity = (from E in Entities.Include("GoodReceiptItems")
                                  where E.ReceiptId == entity.ReceiptId
                                  select E).FirstOrDefault();

            // Update Good Receipt Repository
            existingEntity.Merge(entity);

            Entities.ApplyCurrentValues(existingEntity);

in code above we can see the entity has "GoodReceiptItems" table (50 data)

i need any suggestion for making this matter has good time response or better performance
do you have any suggestion?