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Eventually with the Wine version > 1.3.30 all previous errors and bugs seems to vanish... From now on every Witcher's fan is able to play this wonderful game almost painlessly and without all those problems threatening Linux users for some time...
Game's performance is quite good and it seems constantly improving. There is no need to disable GLSL shaders. However, doing this clearly improves Witcher's 2 performance and makes it much more playable. I can play rather fluently on moderate details settings on a computer equipped with a Intel 9300 Quad Core processor, 2 GBs of RAM and nVidia GeForce GTS 450 graphic card.
There are two changes need to be done in a stock wine configuration before one starts to play. You have to run the following command:
winetricks vcrun2010 d3dx9_36
It is also recommended to disable GLSL shaders with a command:
There are no problems with a clipping sound nor with any mysterious whitescreens.
I'm using the most up-to-date version of the game: 2.0. Unfortunately, I have no idea, if the installer works or not. That is because I did not have install Witcher's 2 recently...
What does not
Everything works fine with two modifications described in the above paragraph.