Ever since i upgraded no problems with performance, even on wasteland servers with loads of players.
My specs are:
Intel Core i7-4770 (3.5, no OC yet)
16GB ram (Corsair DDR3 1866MHz CL10 Vengeance)
Game and win 7 on Samsung SSD840 256GB
I believe SSD has strong impact. I run everything on ultra, 1920*1200, dist. 2500, obj. 1500, shadow medium 100m, AA 4X and even wasteland runs 30-50fps.
Unfortunately arma 3 needs high-end machines :(
(i used to run it on laptop).