FPS reduces when image cropping is done

[nishhhh]

Hi,
I need to crop and save image using nvidia deepstream.
Its done based on the link below

How to crop the image and save

Hi, I am developing DeepStream Programing based on DS 4.0 SDK in Xavier now, I refer to dsexample plugin source and test2 program How do I crop the image from bbox? and then how do I save this image?

But the fps reduces from 30 to 15. For each and every detected object, new nvbufsurface is allocated and this can be the reason.
Any possible solution ?