10 Node.js Event-Loop Hacks for Millions of Requests

Practical techniques to squeeze every microsecond from Node’s loop — without burning the house down.

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Ten proven Node.js event-loop hacks to scale to millions of requests: non-blocking I/O, keep-alive, backpressure, threadpools, workers, and zero-copy tricks.

You don’t scale Node.js by “hoping the loop keeps up.”
You scale it by removing everything that wastes a tick.

Below are ten field-tested hacks I use when traffic spikes into the millions. Each one is small on its own; together, they turn a chatty server into a cold, efficient machine.

1) Make blocking impossible (audit the hot path)

Let’s be real: most Node “performance issues” are accidental sync work. Do a ruthless pass:

• No fs.readFileSync, no crypto.pbkdf2Sync, no zlib.gzipSync in handlers.
• Use async variants or push CPU work off the loop.

Quick trap to catch sync calls:

// naive detector: warn if handler blocks >5ms
const wrap = (fn) => async (req, res) => {
  const start = performance.now();
  await fn(req, res);
  const dt = performance.now() - start;
  if (dt > 5)…