Low FPS in multiplayer

I'll start from the top, when I play singleplayer I can play on high settings at 20-30 fps. But when I go to multiplayer and load up..say "Takistan Life" I will get 5-20 fps on very low settings. I only get low fps in multiplayer, not singleplayer. I asked my friend what the problem is and he said that it's something to do with the "networking" or something..I'm not sure. He said it's a build up of network code, not sure if that's true or not. Ahh, one other thing, I play DayZ with the map "Panthera", i play on normal settings and get 25+ fps. I play on chernarus, I get 15+ fps on very low settings. I'm not sure if this is the "networking" build-up, the map or something completely different.

My Specs -

CPU - Intel Core 2 Duo P8600 2.4 GHz

GPU - Nvidia GeForce 320M

RAM - 2GB

Thanks, Kanga

1st ArmA uses about 1,5 GB Ram so 2 gb with a operation system and everything there is is never enough for it. this lags the game out.

2nd it also depends on the server you play on and your connection to the server.

by example you can run a PC with a six core 3.8 intel wa ever, NVidia Gforce x670watever and 16 gb of ram and still lag masively when you play on a server hosted by someone with specs who can barely run arma itself. or you can play with a super PC on a super server who just happens to be across the world for you abd make your connection to it buggy and bad.

also the reason Panthera and Chernarus are diffrent is because BIS maps are overall way more detailed than most (note that i typed most) maps of the comunity and because of that more requiering.

Thanks for the reply, but I look in my task manager when my game is on and the highest I've seen arma 2 get up to (memory wise) is 800,000. That's only halfway to 1.5 GB of RAM. I also noticed on another forum, a man said this: "Turn Texture Detail, Terrain Detail, and Objects Detail to high. Change Video Memory to default. ArmA is weird, if it's below high it'll run on your CPU (for the above) if it's above high it'll run on your GPU, and as your GPU is half decent it'll make it better, did with me." Im not sure if that works but I'm going to try, what would recommend I put more pressure on; The GPU or the CPU? (Listed Above)

Note: I can also overclock the GPU by 75%.