need a small help

why when i playing in battlefield play 4 free in high or medium Quality its lag and the screen get black and back to the game quickly i want high or medium Quality to see enmeies far away because im recon i have m95 camo and desert balstic scope iwant to kill enmies far away come what is the problem

there is nothing to do. U can go to the (i dont know how do u say it in English) but u can go to that main place that has several thing.
U go to the CPU usage and put BFP4F.exe priorite HIGH, and go put the computar in High Performance and turn off some visual efects of the windows...

carlos G