Use WebSocket whenever you need a near real-time low latency connection between the client and the server. Some examples of use cases:
Multiplayer Online Games
Live Sports Links
Real-time social networking update
the wowonder have for every user 15 requests in 30 seconds, so 15 * 5000 users is 75000 in 30 seconds, but if you are using 200 users, for example, and the requests is 3000, its high still
so your site without websocket will broke with 200 users
with websocket it have not limit, Everything will depend only on your server, and websocket can support a large traffic
That's what facebook uses.