Need help with performance.

[ChaoticKam]

During certain games I am able to get stellar performance on ultra settings (1080p) with my setup. Surprising even my self at some times. But in other games such as Tom Clancy's: Ghost Recon Wildlands I get at max 40 fps if I am lucky and although having an 8gb card, while 4gb is being used its utilizing 100% of the graphics card and 20% of the cpu. Bellow will be attached pictures. What can I do to maximize performance.  (EDT: There is a lot of stuttering aswell)

[TrigrH]

lower gpu heavy graphics settings, monitor GPU temps, overclock and undervolt the gpu.

[ChaoticKam]

1 minute ago, TrigrH said:

lower gpu heavy graphics settings, monitor GPU temps, overclock and undervolt the gpu.

The temps average 70-75 

And I don't know how to do either of those.