My 3570 was runing in light oc , about 4.2 ghz , and gtx 660 first , in last months i used gtx970 until i sold it. But dcs has got more updates etc, and i have 1060gtx 6gbs now with my I3 6100 so it may explain lot.
Anyway, now dcs runs really fast with my 2560x1440 monitor , but i use rift 99,9 % of time..rift performance is ok.
But even quite big missions run fine, so im quite sure that fast single core/and fast memory is Number one thing for dcs , after that comes GPU ..
Old engine + ductape , so 2.5 will come and fix all ;)
Sent when im drunk with my iphone near me :)