@Matches said in When is parallelization not a performance gain?: @Tsaukpaetra Using 'Insert into table values (value1, 2,3) select * from something' is different than 'select * into table from something' The first one is much better in terms of lock contention. I mainly mention it because people tend to get lazy and use the second form, which fucks up badly once things get busy. Yeah. I'm pretty sure SSIS is specifying all the wanted columns individually in the select statement, and in the insert statement it's doing it in batches.