LOW FPS ISSUES WITH 1060

I have an i7 8700 cpu with a gtx 1060 6gb card and I struggle in really open areas. For example when i go to any point on the river that  runs down the map or in the large desert areas my fps tanks to the low 60s sometimes going under (in doors or small areas I get close to 100 fps). I have all of my video settings on low and disabled what I could. I dont understand. Shouldnt my pc be able to run this pretty decently? Especially since I have my settings mostly at the minimum??