Are all instances created equal? Perhaps because under multi-tenancy multiple virtual machines run on the same physical host, not all applications will run equally well on every instance. In that case it makes sense to measure and move to a better performing instance.
That's the interesting idea from @botchagalupe:
Imagine something like a "performance monkey" where an infrastructure is so bound that it can kill lower performing instances automatically.
@adrianco says Netflix has throught of doing the same:
We've looked at killing off multi-tenant instances that have high CPU stolen time...