Why CPU and GPU load so low in the process of opencv_traincascade?..

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I build the project with CUDA module. Well, I think I did something incorrect because GPU load in process of train(8000 pos and 3000 neg) is 6%(Nvidia QUADRO). And CPU: On precalculation stage CPU load is 100%(core i7), but then falling down on 12%, and keep working on it. Can you give me some advise, what I should do? I'm new in OpenCV and want to learn it.