js event-stream head-of-line blocking

main.js

var EventStream = require('event-stream'),
	i = 0;

process.stdin
	.pipe(EventStream.map(function (req, cb) {
		if (i++ % 2 === 0) {
			setTimeout(function () {
				cb(null, "" + req);
			}, 5000);

		} else {
			cb(null, "" + req);
		}
	}))
	.pipe(process.stdout);