Converting files to binary taking hours - Node.js - node.js

Question

I'm reading csv data and then writing it to binary. However, it seems the process of reading in a csv file, converting each data point to a float, and then writing that data to a file takes an insane amount of time. What am I doing wrong and how can I speed this up?
Is this a limitation on node? Should I be using a different language?
var csvStream = csv.createWriteStream({headers: true});
var writeStream = fs.createWriteStream(csvPath);
csvStream.pipe(writeStream);
var binaryWriteStream = fs.createWriteStream(binaryPath, {'flags': 'a'});
Object.keys(dataSources).map(function (dataSource) {
firstPromise = firstPromise.then(function () {
return new Promise(function (resolve, reject) {
var allTheData = [];
var readStream = fs.createReadStream(dataSource);
//stream contents into csv reader
csv.fromStream(readStream, {delimiter: delimiterCharacter}).on("data", function (data) {
//get all data
allTheData.push(data);
}).on("end", function () {
var promise = Promise.resolve();
//for each row
allTheData.map(function (someData) {
promise = promise.then(function () {
return new Promise(function (resolve, reject) {
var someOtherPromise = Promise.resolve();
//preallocate buffer
var buf = Buffer.allocUnsafe(4 * someData.length);
var counter = 0;
//for each individual data sample
someData.map(function (data) {
someOtherPromise = someOtherPromise.then(function () {
return new Promise(function (resolve, reject) {
//convert to float
buf.writeFloatLE(data, counter * 4);
counter++;
resolve();
});
});
});
someOtherPromise.then(function () {
//write buffer to file
binaryWriteStream.write(buf);
resolve();
});
someOtherPromise.catch(function (err) {
console.log(err);
reject(err);
});
});
});
});
promise.then(function () {
resolve();
});
promise.catch(function (err) {
console.log(err);
reject(err);
});
});
});
});
});
});
TLDR:
reading in csv data from files in sequence
allocating and converting the csv data into binary line by line
writing it to a file
With this methodology it takes me five hours to read 614 files and subsequently read, allocate, convert, and write 99 million samples to a single unified binary file.