Activision Assist here to help. This thread may be seen best if it were in the Black Ops 2 forum as this is for Black Ops 1. None the less...What system are you playing BO2 on? What is your connection type, wired or wireless? If you could let us know your in game NAT/Bandwidth from the game's System Info screen it will help us troubleshoot. You can obtain this information by going to the game menu under Options>System Info (for PS3 - Select Button / for Xbox 360 - Back Button).
Activision Assist ^JH