Get online status for a user who is not in the roster

I know there is a plugin(presence service) that allow me to pull anybody’s presence inforamtion for openfire server. Is there a better way to get a person’s online status who is not in your contact list? My administrator worried that if I have to pull the online status through presence service, I have to do it every 3-4 seconds, and it may affect the server performance.

anybody has better idea how to do it?