Same problem, i5-4670k here. And you know whats really funny? Sometimes the whole day i have perfect stable locked 70 fps. But on the next day i have 40-60 and 100% cpu load. I swear this is not the first time this happens. I noticed that so many times, like one day i have perfect 70 fps without any drops and next day i have terrible fps dropping down to 30. DICE says upgrade your cpu. BUT YOUR GAME WORKED JUST FINE 3 DAYS AGO AND TODAY ITS LAGGING. It's definately some issue with the game not with our cpus. And dice probably will never fix that so i guess i have to go to BF4 and thank you dice for great optimisation.