You'll want to look and see where the most time is spent, mailwizz shows timestamps for all actions so you can compare and see how much time is spent for each action. When you start observing a pattern, you'll get the culprit. Make sure you disable pcntl if you want to get clear readings.
But if im right. When i run that command it fires off 500 at a time correct? So I will have to keep doing this until my 120k emails are up? That sounds like alot of time.