@HeelX: In the final version the process will look like this:
1. You tell the renderer which models get a shadow (via a flag or a Light Manager)
2. The dll checks which objects need shadows and render them. If the models have an alpha channel in their texture, the shader uses the alpha channel and render it.
I hope this will help to understand the process.

@ dark_samurai: the problem or "bug" you see, only happens if your framerate is down, because the shadow is a post-processing-texture. I can change that and render the shadow directly on the models, but than you can't use the soft shader... well I will try to make the render process faster, so you won't see the "bug", but it's just a try...
It is really strange that it runs so slow on your machine, maybe its because of the physX, the rest is only a box and a plane, so only a few vertices points to render

sorry for my bad english, but I'm damn tired today.
Greetings from bavaria
Chris