I think that they made it so that if you have a three bar connection, it is almost like a two bar. It is opening week so there is high traffic and it should progressively get better.
MW3 has constant lag in the gameplay just like MW2
Lets say you're running and you're getting shot at and you get to cover behind a wall but somehow you die behind it, you watch the killcam and it shows you were not even behind the wall on the guys screen..Its stupid and the most annoying this in MW2 & MW3