Questing on testing Google Cloud CUDA usage

Hi everyone

I try running a VM using Google Cloud instance with a GPU and feel confusing when running test script from

From the picture, I start by running CPU then GPU. The result in the second picture is what is expected. But actually the gap from when I run the command for GPU and when I get the result is like half a minute or more while CPU is just a few second.

Anyone know what is happening here?