[Solved] Call of duty MW3 running slow

hello all, i have just installed cod mw3 and its oka0y but only when it comes certain parts, the game runs slow and sometimes freezes and after 5 or 10 sec it runs smoothly again. but it becomes worse especially during loading before a level.

i am running the game my asus k43u laptop. it has
2gb of ram
an AMD E-350 processor 1.60 ghz
a 64 bit os (windows 7)

please let me know if there is something i can do to improve the game's performance