why HD Graphics 630 run classification slower than i5 7500 CPU?

[mahaoyanghb]

my environment:
windows 10 enterprise
cpu: i5 7500 3.4GHz 4Core
graphics: HD Graphics 630

I download this code ,and compile it by instruction in this website.
I add some code to measure forward time by clock() function.
clock_t start, finish;

start = clock();
for (int i = 0; i < 10;i++)
{
classifier.Classify(img);
}
finish = clock();
std::cout << "cost " << difftime(finish,start)/10<<" ms"<< std::endl;

after I compared GPU mode and CPU mode, I found that classification.exe runs 10 times slower in graphics mode than in CPU mode .
CPU : 8ms
HD Graphics: 80ms

HD graphics card should run faster than CPU , shouldn't it ?
why it runs much more slow?

remark:
OpenCL is downloaded from intel
I have checked caffe recognize the true opencl dir.
the only change is I remove the HAS_HALF_SUPPORT definition , because clblas.h don't have half precision functions.

does anybody know the reason?
Thank you very much!