Call of Duty cod lag

Using R4 SDHC with 4g chip. Is this normal for this game to lag so much? Is there any way to fix it. Since I do not own the original personally, I am not sure if it lags on that one. This is a very cool game but hate the lag when it happens. Anyone know a way to fix?Thanks

Which one is it? CoD 4, CoD WaW, or MW Mobilized?

I think it's normal because the game is big for a DS to handle. because it has alot of open areas and a bunch of enemies at the same time
i cant remember if it was a non-r4i review or r4i review
but they said "Dementium 2 didnt lag at all like COD"