Native iOS code runs slower with Unity

This is a very specific problem I'm facing when working with a native iOS library and Unity3d. The performance of the library goes down 2-3x times when we integrate with Unity, as compared to when the native code is built as a native app (without Unity). The native library basically spawns a separate thread and performs some image processing computations. Both the with and without Unity versions calls the same library code. The without Unity native app renders some OpenGL primitives using...

Native iOS code runs slower with Unity