Just as an info: SLI or Crossfire DO NOT DOUBLE YOUR VRAM. The information has to be saved twice (once on each card). The lesser fpslag in towns for those people is due to their HDD being way faster (at least that's the case for everyone I know :P)
Also the texture size isn't that big. Even if you lower the texture detail the fps hit in towns will still be big. That is 'cause the game is split into many small files that are not accessed in order. SE just failed to implement an async loading mechanism like in UDK.