Hi all,
If I stay with non-LAA version of the exe, everything works fine, until few minutes of playing, when textures start to turn purple or black. I'm aware that this is likely out of memory issue.

So, when I patch it to the latest patch (1.3.1) or install a mod that patches the exe for 4gb aware, in both cases there is significant FPS loss and, worse, the shadows start flickering like crazy.

SO it's between, purple and black textures and FPS loss and shadow flickering.

Neither are particularly pleasing options..

Turn down the settings so that once you give the game enough memory to use those settings the resulting increased taxation on the rest of your hardware doesn't slow the game to a crawl? Just a thought.