At Heroku, free applications get idled out when no request comes in for a while. As a result, when the first request comes in after some time, it can take a few seconds to find a piece of iron to run the process on, run it, and hook up all the tubes.
The advantage is you get to run arbitrary code rather than, say, serve static pages, though.
I'm sure someone will correct me if I'm wrong, but I'm pretty sure that's only true if you're on the free level (i.e. only running 1 dyno). Otherwise, your process is always active.
The advantage is you get to run arbitrary code rather than, say, serve static pages, though.