Indexes are useful when reading data. But when inserting data into a table, it may be useful to disable the indexes and rebuild them again after insert operation completed.
Especially when loading huge data manually or with ETL, disable index on pre-sql and rebuild on post-sql:
----Diable Index ALTER INDEX [IX_Index_Name] ON dbo.TABLE_NAME DISABLE
----Enable Index ALTER INDEX [IX_Index_Name] ON dbo.TABLE_NAME REBUILD