I've found out that it's Shade-c that affecting the shadow stencils kills my framerate completely.
Probably the depth of field tries to blur the shadow stencils too and those calculations being done realtime are the reason for my fps being killed.
Is there a way out of this? Can I set shade-c not to interfere with shadow stencils? or even better can i set shadow stencils to be rendered once for static objects like a wall. while they continue to being rendered realtime for my player?