Dynamic linkage performance loss after adding more class implementations.

I found weird behaviour on GeForce 760 GTX card. When using dynamic linkage at some point adding another class implementation causes performance loss even though this class is not used during tests.(This class instance was not assigned to interface variable, but the fact that it could be done during application running caused performance loss). I did not found such dependency on AMD cards. Is it possible that NVIDIA does not support DX11 dynamic linkage mechanisms properly?