What sp332 said - there wouldn't be any extra steps as you would have to go to your email to complete registration anyhow.
You could have an extra link in your email which lets you update your existing registration details with the ones you've just entered, but that's not going to significantly extend the amount of time you take to register.
You could have an extra link in your email which lets you update your existing registration details with the ones you've just entered, but that's not going to significantly extend the amount of time you take to register.