I am considering Passport since it seems to have pretty good documentation, but I want to make sure I'm not missing out on something better. This app could have a ton of traffic, so I am trying to build it very efficiently right from the start.
If you're using bcrypt for authenticating passwords, that may end up being the most compuationally-expensive part of your entire application.<p>Consider running your authentication service as a separate node server so it can scale independent of the rest of your application.
It's unlikely you'll have efficiency problems at the user acquisition stage.<p>It's generally 1 insert into a user table.<p>The most important thing is your users security. The passwords need to be hashed and salted.