Node can use several threads, even if you only write JS

parallel.js

const fs = require("fs");
const util = require("util");

const readFile = util.promisify(fs.readFile);

async function long() {
  const content = await readFile("./dummy1000000.csv", "utf-8");
  content.split(/\n/);
}
const arr = [];

for (let i = 0; i < 10; i++) {
  arr.push(long());
}
Promise.all(arr).then(() => console.log("wicked parallel dang"));