To elaborate what Wiz said...
Ping kind of deals with network speed. If your Ping is high, you will notice things moving very slowly, jagged or jerks about. Everyone's ping setting is different but you want to have a
low ping so you can move more fluidly. Sometimes its not your fault; the server you maybe connecting to is very far from where u live, so you will have a higher Ping which means the network needs to work more harder for you to play at a decent pace.
Typically, a good ping would be 50-100
Bots or players playing on their own server have 0 ping
I hear if you go into your console (by hitting the tilde "~" key) and type: /snaps 40
That will reduce your ping about 20-40.
Also, change your network setting to correct speed you have at home. If you are using a cable modem, set it to the cable modem setting.
Hope that helps...read the openarena tweaks as well from
www.openarena.ws ... in the Wiki section.