LOL. Ignorance.... haha
U say it´s all because of PSN. That´s not true. Zombies mode is lagging always, online and offline, in COD WaW and in COD Black Ops. It´s not because of the PSN, it´s because of the ****ing poor port of COD games from Xbox to PS3. In MW3 the development is splitted in 2 ways, one for PS3, and one for XBOX, which is going to save us of this bugs.
So, yeah, it is your GAME, it´s not PSN.