It's interesting to see how the code pulls it off. If you run Profiler while this runs, you'll see a table variable being created, and then an insert statement

It's interesting to see how the code pulls it off. If you run Profiler while this runs, you'll see a table variable being created, and then an insert statement for each row into that temp table. My guess is that the main performance gain comes from inserting into a table that doesn't require checks against constraints, etc., but eventually the overhead for all those individual inserts means that SqlBulkCopy wins out. And, the need to define your UDTs is a bit of a pain. But to prevent a glut of UDTs in the db, I've tried to make common UDTs that would commonly be used, such as CREATE TYPE [dbo].[udt_IntTable] AS TABLE( [Item_Key] [int] NULL ) One more point: it's probably best practice to use the TypeName property when using these, as it's required when using a UDT against a parameterized statement that's not a sproc. param.TypeName = "item_drop_bulk_table_rev4";