There has been proof that the D2D and retail versions of the game have there FPS crippled because of DRM!
for anyone with the reatail or D2d version of the game , read below
If you replace your Witcher2.exe and paul.dll (perhaps optional) with the GOG version, you will gain 30%+ to your FPS almost guaranteed. I tested this myself: Whereas I was hitting 20-28 FPS in Flotsam, I now hit 30-45 FPS STABLE. It is a huge increase, and totally noticeable. It will also stop the game from taking 15-45 seconds to load from the launcher! The game now loads almost instantly for me, whereas before it took +15 seconds when starting the game in Windows, even on my fast Vertex 2 SSD.
for anyone with the reatail or D2d version of the game , read below
If you replace your Witcher2.exe and paul.dll (perhaps optional) with the GOG version, you will gain 30%+ to your FPS almost guaranteed. I tested this myself: Whereas I was hitting 20-28 FPS in Flotsam, I now hit 30-45 FPS STABLE. It is a huge increase, and totally noticeable. It will also stop the game from taking 15-45 seconds to load from the launcher! The game now loads almost instantly for me, whereas before it took +15 seconds when starting the game in Windows, even on my fast Vertex 2 SSD.