How long (ms) for email send flow step?

At Marketo Summit, there was a great presentation by Scott Nash on batch campaigns, and he showed a slide with these average wait times:

Add to List - 36ms

Add to Nurture - 100ms

Change Data Value - 81ms

Change Nurture Cadence - 42ms

Change Nurture Track - 56ms

Change Score - 139ms

Remove from Flow - 147ms

Remove from List - 40ms

Request Campaign - 129ms

Send Alert - 11,530ms

Change field in Program - 29ms

Change field in Progression - 64ms

Interesting Moment - 40ms

Send Email - 5,180ms

Update Segmentation - 76ms

I'm trying to understand how 5 seconds for a send email flow step can be accurate. That would mean it takes 138 hours to send 100,000 emails. Am I missing something here?

-Jon