Ok so my PC specs are: 6 core AMD CPU 4850 AMD GPU 8GB Ram
My setting are like medium and i usually have 80-130 fps.Although sometimes something happens and my fps get capped to 40.When this happens my fps cant get higher than 40,even in final killcams when nothing happens.Then after a while it lags for half a second and it goes back to 80 fps.Is it a bug?
More aboutblack problem
Is your GPU Oced?The GPU may be reaching high temps and drops performance so it cools down. Run HWmonitor and start the game,when the fps drops begin look at the temps.
Video Card temp is 64C when it happens.Dont really think its the temp problem since it doesnt happen in any other games.