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, because there is not so many people playingon weak cpus, so i guess i have to go to BF4 and thank you dice for great optimisation.