Deleting huge set of data from a table in SQL Server by DELETE command is costly, because the deletion is logging each row in the transaction log, and it consumes noticeable resources and locks. Use TRUNCATE table command instead if you want to quickly deleting the data without locking the table and writing the log file. It took almost 1 minute to delete 2-million records in a test database with DELETE command, and only 1 second with TRUNCATE command.
Note that it's possible to rollback the data after DELETE command is executed, but not for TRUNCATE command.
