Hmm, I see. PythonAnywhere web apps get their processor power from the number of worker processes they have running; so, for example, an app with 10 workers can handle 10 simultaneous requests. Web requests tend to be very short-lived things (request comes in, quick database lookup, render a template, return) so you can support a very large number of hits/second with a small number of workers. I think the current record-holder is handling several million hits a day with ten workers, for example... though that is a particularly well-optimised site.
Anyway, what you're talking about sounds like it would need to be implemented as a website with a base number of workers that auto-scaled when the workers became busy. That's certainly something we've discussed in the past, but we don't have a feature to do that yet :-(