GWX laggs

[birdy]

hi all,

when i play silent hunter with GWX, i am very lagging. even when i play without the High setting, im still laggy when i am under attack and stuff. also the loading times are very long, when i start a mission or my campaign the loading takes over 7 mins!
but when i had GW and stock sh3 i had no laggs, and i think my system is also good enough ( i have a 512 videocard, pentium 4 and 1024 mb memory).
does any1 know how to solve the laggs?
thx

ow and another question: what is anti-aliasing and how does it work??