from main.js it works fine... (?)

noproblem.js

var str = '';
var n= 1024*1024;
var i = n;
while (i--) str += "C";

console.log('str.length -> ' + str.length);

var maxT= -1;
var save= [];
(function loop () {
  
  var t0= Date.now();
  var buf = new Buffer(n);
  buf.write(str, 0, 'utf8');
  t0= Date.now() - t0;
  
  if (t0 > maxT) console.log("max time -> " + (maxT= t0) + 'ms');
  if (save.push(buf) > 100) save.length= 0;
  process.nextTick(loop);
  
})();