Message import slows, takes hours; indexing problem?

New user. I was importing from Outlook, initial rate was about 600 messages per minute. After 14 hours, rate was down to 130 messages per minute.

My impression is that the SQLite database has indices which were being updated with every insert, rather than disabling the indices and rebuilding after load is complete.

Is there a way to address this? If so, I would like to purchase the individual user license.