A long-running `next dev` session (Next 16.x) forks a child process from `.next/dev/build/postcss.js` roughly once per second and never reaps it. Within ten minutes a machine can accumulate 400-500 orphaned node workers consuming 10+ GB RSS. Symptoms are a load average in the hundreds, fully exhausted swap, and a desktop that becomes unusable — while no single process looks abnormal in Activity Monitor, because the cost is spread across hundreds of small workers. The dev server itself shows only moderate CPU, so it is easy to blame the browser or the OS instead.