That's basically what I was going to say. I've developed a realtime system for my company that uses a REST API on the backend, but we use websockets to push updates to the clients in realtime. It's so much faster (no polling and no overhead of establishing new connections). When there's an update we hit the API once to fetch the new data and then push it out to all clients subscribed to the given data set which massively reduces load on the server.