Bulk Copy and Indexes
If your table has a clustered index and the data to be inserted is ordered to match the clustered index key, bulk copy the data into the table with the clustered index already in place and specify the ORDER hint. This is significantly faster than creating the clustered index after the data is copied into the table.
If nonclustered indexes are also present on the table, drop these before copying data into the table. It is generally faster to bulk copy data into a table without nonclustered indexes, and then to re-create the nonclustered indexes, instead of bulk copying data into a table with the nonclustered indexes in place.