why is GPU version is slower than CPU version?

[duwangthefirst]

I've run the demo and find that the object detection process runs faster with option "CPU" instead of "GPU".
Is this NORMAL ?
I 'm using:

• ncnn_20210720_android_vulkan
• opencv_mobile_4_5_3_android
• gradle 6.7.1
• gradle plugin 4.2.2

[nihui]

https://github.com/nihui/ncnn-android-nanodet#some-notes

Most small models run slower on GPU than on CPU, this is common