Alright, forgive my ignorance since I'm a 3D artist not a programmer, but these whatever shaders are actually slowing down framerate only when they are applied to concave meshes.

Somebody I know mentioned about "tangent calculations" slowing down. ???

Cause the shaders run fine and maintain a good framerate when applied to mdls.
But mdls don't cast shadows unless it's realtime, and not pre-rendered.

So

In case 1
I use mdls with normal maps but the shadow stencils realtime kill my framerate.

In case 2
I use concave meshes with pre-rendered shadows but the normal mapping shaders applied to them kill my framerate.

Jeez I'm just trying to have normal mapped models with their shadow stencils in a scenario and mantain a decent framerate.

But it's starting to feel like asking for a miracle. Can anybody REALLY help out here please?