Is heroku's free instance loaded on demand? If not that would be cool as startup times on the ep.io dynamic instances are v slow.
I've been scaling mine around, and it's never taken more than a second or two. Although, maybe that would change if you are scaling up to hundreds of workers or something like that.
It's common in free versions of such services, to only load things on demand, which is a little slow --in Google App Engine you can pay to have instances pre-loaded.