AME barely uses CUDA and CPU powers to render

While it says to use GPU acceleration as render, but AME is painfully slow and so is AE internal render. That's because it barely uses the available CPU and CUDA to render.

It uses less than 18% of six-core CPU and less than 1% of CUDA. I have enabled CUDA setting, what's the deal here?

Windows 10 Pro 64

48GB RAM

Xeon 6 Core 4.3Ghz

GTX 1080 Ti +  GTX 1070