[drogus]

Worker threads can't handle I/O, so a single process Node.js app will still have the connection limit much lower than languages where you can handle I/O on multiple threads. Obviously, the second thing you mention, ie. multiple processes, "solves" this problem, but at a cost of running more than one process. In case of web apps it probably doesn't matter too much (although it can hurt performance, especially if you cache stuff in memory), but there are things where it just isn't a good trade-off.