I am working on a file import of 43 million records on a table that is truncated and reloaded with this import each week. There is an index on one of the fields. If I drop the index and then reload the table , and re-create the index, the process finishes in 10 mins. If I don't drop the index first and try to insert, the process doesn't finish in an acceptable timeframe. Where is all the extra overhead for the insert when the index is left there? Is this purely a disk bottleneck or more than that?