For 2 days ago I upgraded my system with a new MSI gtx 1060 6gb gaming X from my older, slower and above all too little Vram. Gtx 750. So now I have more Vram and that will make P3d happy but I didn't get a very big peformece boost. In dense areas at evening and clouds I can get down to 15-18 fps. Is my CPU, I5 4460 bottlenecks? Would not be so strenge. If it bottlenecking how can I get more load on the gpu because it's quite powerful and now the GPU usage is only around 40-60%. And the cpu works the heck out of it. 

You shouldn't have any bottleneck with that CPU, it's the P3D that can't handle hardware well. One test for CPU bottleneck, try intense titles like Battlefield 1, The Witcher and GTA 5 (CPU intense) if you see your CPU with Afterburner working around 80% than you may have bottleneck, but I doubt that.

You shouldn't have any bottleneck with that CPU, it's the P3D that can't handle hardware well. One test for CPU bottleneck, try intense titles like Battlefield 1, The Witcher and GTA 5 (CPU intense) if you see your CPU with Afterburner working around 80% than you may have bottleneck, but I doubt that.

Okay, then I maybe don't have a CPU bottleneck. But can I get little more load on the GPU or can I just deal with it.

I have a i7 6700k with EVGA GTX 1080 Classified, and I never enough GPU load, what I do and helps a bit is to enable the K boost on EVGA Precision X

If I understand right does the CPU take care of terrain and GPU the rest of it. So how can i get the GPU work more?

My GPU gtx 1060 is more powerful and the cpu is little too weak in dense areas.