How can I migrate large amounts of data if migration performance is poor?

If migration performance is poor due to throttling, bandwidth, capacity or any other reason, you can plan your migration as follows:

Migrate all calendars, contacts, tasks.
Migrate emails for the last X days.
Switch users to their new system.
Migrate the remaining data in the background.
For more information about Delta migrations, click: https://bittitan.zendesk.com/hc/en-us/articles/115008098987