IMB_buffer_byte_from_float for "predivide" case was doing two function calls per pixel. Make it do the work with one function per pixel. Do the same in IMB_buffer_byte_from_float_mask. IMB_buffer_byte_from_float on one thread, running on 4K resolution image, on Ryzen 5950X (Win10/VS2022): 27.4ms -> 24.4ms Pull Request: https://projects.blender.org/blender/blender/pulls/127308