why gpu is slowly than cpu in get_face_boxes?

[tms2003]

I try to run gpu model like this:

python get_face_boxes_gluoncv.py --gpus 0

I get this:

[19:46:58] src/operator/nn/./cudnn/./cudnn_algoreg-inl.h:97: Running performance tests to find the best convolution algorithm, this can take a while... (set the environment variable MXNET_CUDNN_AUTOTUNE_DEFAULT to 0 to disable)
Inference time:16.246319ms

,my gpu is rtx2060. and I try to use default cpu (inter i5),I got this:

 python get_face_boxes_gluoncv.py 
Inference time:18.076420ms

so ,why it is no difference between them ?