What I meant about asking why you're using a Nano, and now that you're saying for the 'horsepower', is because the ESP8266 outspecs the Nano, in case you weren't aware. Nano 16MHz, ESP8266 80MHz, at least double the memory, etc.
Meaning, what purpose is the Nano serving if your project, whatever it is, could be done just on the ESP8266 itself? Yes an Arduino can communicate serially to an ESP8266. But it begs the question. Consider if you even need to.