Improving Node.js https request performance

The HTTPS module of Node.js allows making HTTPS request to other servers. Unfortunately, making requests with this module often leads to poor performance.

I found that calling a nearby HTTPS server usually took between 300 ms and 150 ms.

With the following simple solution, I was able to reduce this time to less than 40 ms.

By default, Node.js does not keep SSL connections alive. Thus, a new handshake has to be performed for every request. If you make many requests to the same server (a very common situation when dealing with APIs), it makes a lot of sense to keep SSL connections alive. This can be accomplished as follows:

var agent = new https.Agent({
 keepAlive: true

var options = {
 host: '',
 port: 443,
 path: '/admin/metrics/main.json',
 method: 'GET',
 agent: agent

var req = https.request(options, function(res) {

  var str = "";
  res.on('data', function (chunk) {
     str += chunk;

  res.on('end', function () {
     // done


req.on('error', function(e) {
   // error

Note here that a https.Agent is created with the parameter keepAlive: true. This agent is then passed in the options for the request. You can use the same agent for all requests.

Using this should significantly speed up making requests to the same server.

You can find the example code I used to test this here:

More Resources

Speed Up Netty SSL

Knowing Where You Are

First you can do a few simple test to see how good (or bad) your current SSL configuration of your Netty server is. Note: These tools also work with any other web server.

  • Perform the wormly SSL Web server test on your server to get an idea how well your server is configured.
  • For a more comprehensive test, consider to use the tool sslyze, which will test your server SSL configuration.

Just download their executable from, unpack the repository and run

sslyze.exe –regular

The test might run for a while but will generate a very informative report.

Improving Netty Performance

Depending on your results in the first step, you might consider the following ways to improve the performance of your Netty server:

  • Assure to keep HTTP connections ALIVE.

This requires to send a ‘Content-Length’ header to the browser and not to close the channel after a response has been written to the channel.


Stackoverflow – Slow Java SSL in a netty application

5 easy tips to accelerate SSL