when a realtime dashboard needs to push thousands of events per second to dozens of browsers, a naive ws.send() loop can saturate the V8 event loop, drop frames, and eventually crash the server. i ran into this while extending a Next.js API route to broadcast sensor data from a Rust edge worker. the problem isn’t just bandwidth – it’s how quickly the Node process can drain its internal socket buffers.

why back‑pressure matters

Node’s WebSocket implementation respects the underlying TCP back‑pressure: socket.bufferedAmount grows when the OS can’t keep up. if you keep queuing messages without checking that metric, the process memory spikes and GC pauses become noticeable. the usual pattern of for (msg of msgs) ws.send(msg) ignores this signal, leading to “write after end” errors when the client disconnects mid‑burst.

a bounded queue solution

instead of hammering the socket, we can introduce a fixed‑size async queue.…