Questions about socket.io

If i have a chat with for example 100 users online.
Currently I’m using AJAX to check for new messages/users/rooms etc…
If i convert it into socket.io instead of ajax requests, will it help me in terms of server’s cpu usage
or make it worse?
because maybe I won’t have so many http requests to the server per second, but i’m wondering if having
so many consisted connections won’t make it even worse.