Benchmarking performance of the migration

Migrate allows you to benchmark the migration and get execution time.

$ drush mi Migration --instrument // Capture performance information (timer, memory, or all)

To add custom tracking you can surround your code using

migrate_instrument_start($descriptiveName);
// your code
migrate_instrument_stop($descriptiveName);

You can get periodic feedback using

$ drush mi Migration --instrument --feedback="1000 items" // Display a progress message every 1000 processed items or less