VPI Library, use of functions with U8 image issue

Hello i have an issue with using the functions of the VPI-library with an U8 input image.
If I put an RGB 8 image into the rescale function in C++ everything works fine, but if I put a grayscale image into the rescale function I can see a little delay in the Nsight System.
Before the rescale operation the CUDA-API-function cudaCreateTextureObject gets called and after the operation the API-function cudaDestroyTextureObject gets called.

How can I prevent the call of these functions?