Why does COD4 mp lag on my pc?

Question

single player runs smooth on highest graphics and with 4xAA

so why does it lag in multiplayer even on lowest? i play with friends over a LAN connection through our home router, it doesn't lag on theirs not even the laptop going over wireless.

I have tried looking on the internet for a solution it seems other people have the same problem but i never found an answer for xp.

Yea so Im running windows xp service pack 2.

o and i don't think its a hardware problem as it runs fine in single player like i said, it even lags in the mp menu.

Unreal Tournament 3 runs smooth in multiplayer even on highest.

I remember I also had the same problem with Call of Duty 2 mp last year and Ive got a new graphics card since then

Answer 1

your firewall might be restriciting the game. i have a question did u buy call of duty 3 because if you did and that didnt lag call of duty 2 and 4 were made by a different company to call of duty 3

Answer 2

It may lag because of firewall, you  might be downloading it.

It could be the servers you go on HIGH PING servers are bad because they are further away means lag.

Try going on servers which have low ping like less then 150