I think it has been discussed a few times, game has a horrible memory leak, leading to a lot of the problems. RW, the programmers, have yet to fix this issue in newly released games, so it is either an intrinsic problem with the engine... or they just made the same mistakes again... or they have no clue how to fix it.
Poor GF, I feel bad for them that RW doesn't seem to care or have the ability to fix it.