C vs Node.js: I fought the Event Loop, and the Loop (almost) won

The Hypothesis

I love C. It’s raw, it’s low-level, and it forces you to understand memory. Naturally, I assumed that a raw TCP server written in C would obliterate a server written in JavaScript (Node.js).

Node.js runs on V8 (a JIT engine) and carries the weight of a runtime. C runs directly on the metal. The winner seemed obvious.

I set up a benchmark between my Surface Pro 9 (Client) and my Ubuntu Homelab (Server) over a Tailscale VPN.

Attempt 1: Node.js (The Baseline)

I ran a standard “Hello World” in Node.js, which uses the Event Loop (Non-blocking I/O) by default.

• Requests/Sec: ~15,860
• Errors: 0

The Reality Check: Node.js didn’t just win; it destroyed my C server. It handled concurrency effortlessly because it never waits for I/O.

Attempt 2: The Naive C Server

My first attempt was a standard, blocking C server. It used accept(), write(), and close() in a simple while loop.

I hit it with wrk (12 threads, 400 connections).

• Requests/Sec: ~6,500
• Errors: 160,000+ (Socket Read Errors)

The Failure: It was a disaster. Because the server processed requests one by one (Blocking I/O), the OS connection queue filled up instantly, and packets were dropped.

Attempt 3: The Redemption (Single-Threaded Epoll)

I wasn’t going to let C lose. I rewrote the server using epoll, the Linux kernel’s high-performance notification mechanism. I also implemented HTTP Keep-Alive to stop closing sockets unnecessarily.

• Requests/Sec: ~13,580
• Errors: 0

The Frustration: I fixed the stability, but I was still slower than Node.js. Why? Because libuv (Node’s C core) and V8 are hyper-optimized. My single-threaded C code just couldn’t keep up with 15 years of Google engineering.

Attempt 4: The Nuclear Option (Multi-Threading)

Node.js is single-threaded. My server has 4 cores. It was time to cheat (or rather, use my hardware).

I used pthread to spin up 4 worker threads. But how do you share a port? I used SO_REUSEPORT, a Linux kernel flag that allows multiple sockets to bind to port 8080 simultaneously. The kernel handles the load balancing.

• Requests/Sec: ~17,060
• Errors: 0

The Verdict

We finally did it. We beat JavaScript.

Conclusion

I started this experiment to prove C was faster. Instead, I learned that Architecture > Language.

A badly written C program will always lose to a well-optimized Runtime. Even a well-written single-threaded C program might lose to the V8 engine. But if you dig deep enough into the OS using epoll, SO_REUSEPORT, and threads you can eventually reclaim the crown.

Check out the source code for the final server on my GitHub.