Mostly it depends on your hosting provider, which blocks you after some number of requests.
Try to change polling interval:
For chat, in /styles/.../templates/chat.tpl change frequency argument:
var threadParams = { ...... frequency:2,
For "Awaiting Visitors" page, add frequency argument (2 secs by default):
var updaterOptions = {
.... noclients:"<?php echo getlocal("clients.no_clients") ?>", frequency: 7 };
Evgeny.