Why the lag in online servers?

[MaXMhZ]

IL-2 1946 runs on my Atom 330 ION under Windows 7 Ultimate 32 bit, but nowhere nearsmooth. Flying a single plane on an empty small map without objects like trees or even worse buildings will get me just about 20 - 30 fps.

I think the 2 GB is the biggest problem here. I am running 4GB DDR2-800 dual channel in my atom. The ION is much more capable than the Intel integrated graphics too, and the Atom is a dual core with hyperthreading (4 threads).