The COD games work via P2P connections hence the most likely cause is because you're having to connect to a host that's on the other side of the world to you. Before anyone comes in with their "dedicated servers would solve all these problems, bring about
world peace and give Barack Obama the finest beard since Lincoln" they'd cause the same problems. Since dedicated servers would likely be located in the States North American players wouldn't see too many problems if any. However if you're based outside of
the US/Canada/Mexico you're still having to connect to a server on the other side of the world and you'd run into the same distance problems that afflict P2P.
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