too slow on PC

[xhzzhang]

In my PC(GTX 1080), the model 'MobileNetSSD_deploy.prototxt' from https://github.com/chuanqi305/MobileNet-SSD.git, result is to slow, like below:
...
ime = 453.379 ms, FPS = 2.20566, Average time = 454.742, Average FPS = 2.19905
time = 451.781 ms, FPS = 2.21346, Average time = 454.623, Average FPS = 2.19962
time = 454.534 ms, FPS = 2.20005, Average time = 454.62, Average FPS = 2.19964
time = 456.311 ms, FPS = 2.19149, Average time = 454.682, Average FPS = 2.19934
time = 454.466 ms, FPS = 2.20039, Average time = 454.675, Average FPS = 2.19937
time = 454.85 ms, FPS = 2.19853, Average time = 454.681, Average FPS = 2.19935

[rocking5566]

ncnn inference on CPU. It does not support GPU.