I already have that, this is a real issue, not a client side setting thing...
If it is a real issue it is not related to the Open Arena client you are using, if it was it would have been reported a few thousand times until now. I think it is a real issue as far as your setup/configuration/hardware goes. Hence I suggested client related settings first. I would now suggest that you check your router, switch, firewall and even possible your antivirus if you are running any for errors or high loads. Restart of various services/programs can also make a difference. If you are having software programs such as MSN, IRC or other pinging/heartbeating programs, then close them as this will improve your connection. If you are you linux use netstat and see where requests are being passed. If still nothing, then contact your ISP and see if they have error correction enabled on their TCP/IP, if so, ask then so disable it.
And no, I did not imply that you were noobish, I did something to try and help instead of ignoring a request for help. So feel free to try any of the suggestions I provided, unless they are to simple for you..