TL;DR NodeJS processes runs on a single process, which means it does not take adavantage from multi-core systems by default. If you have an 8 core CPU and run a NodeJS program via
$ node app.js it will run in a single process, wasting the rest of CPUs.
Hopefully for us NodeJS offers the cluster module that contains a set of functions and properties that help us to create programs that uses all the CPUs. Not a surprise the mechanism the cluster module uses to maximize the CPU usage was via forking processes, similar to the old fork() system call Unix systems.»