title: Mongo tailable cursors vs Redis pub/sub
body: <p>I'm backing a real-time websocket server application with MongoDB.</p>
  
  <p>The client base is growing, and single-threaded performance is no longer enough. I need a pub/sub layer to distribute messages across threads.</p>
  
  <p>I would normally go for Redis, but since the app already uses MongoDB, I could avoid the dependency using tailable cursors. However, I worry about performance.</p>
  
  <p>How does MongoDB's tailable cursor performance compare to that of Redis for a pub/sub architecture?</p>