There are a lot of factors including the network overhead mentioned by jjgraf. You didn't mention how you are importing the text file - SQL Server offers several options depending on the version.
Bulk inserts using SQL Server are generally very fast. However, if the proper options are not set the import process may not use bulk inserts. You may also be dealing with overhead of growing transaction logs and maintaining indexes on the tables. Perhaps, you can provide some more details about the import process. Terry L. Broadbent
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