Overheads for using btSoftRigidDynamicsWorlds

[SynapticBytes]

I'm trying to implement a Bullet plugin for Shiva3D and am up to implementing soft bodies.

Because I don't know until runtime whether the users wish to create soft bodies or not, I am currently creating my physics world as a btSoftRigidDynamicsWorld, even if the user is only using rigid bodies. Justly creating a softbody world instead of a rigid body world, is there likely to be any significant performance or storage impacts?

The alternatives are few due to C++ not having a ducking mechanism. I would need to add significant code to upcast/downcast and use temporary variables to convert in appropriate places, or have two versions of my plugin for each world type, and then maintain 2 code bases, which is not viable.

Anyone have any ideas?

Thanks.