Why is spawning a new process in Node so slow?

Node.js has been observed to have slow performance when spawning new processes, particularly under load, with a maximum of 40 spawns per second and significant main thread blocking. This issue was highlighted in a benchmarking exercise comparing Node.js with Deno, Bun, Go, and Rust, where Node.js performed the worst, handling only 651 requests per second. In contrast, Deno and Bun achieved over 2,200 requests per second, while Go and Rust reached over 5,000.

To address the performance bottleneck, various strategies were explored, including using Node's cluster module to spawn multiple processes and distribute requests. This approach improved performance to 1,766 requests per second but still lagged behind Deno and Bun. Another method involved moving spawn calls to worker threads, which resulted in even lower performance due to the overhead of coordinating between threads.

Ultimately, switching to child processes for handling requests yielded better results, with Node achieving 2,209 requests per second when using child processes. The exploration also included attempts to optimize logging and output handling, with mixed results across different implementations. The findings suggest that while Node.js can be improved through various techniques, it still struggles to match the performance of compiled languages like Go and Rust, as well as newer runtimes like Deno and Bun.