Thats odd, I tried playing the Karkand maps yesterday and found it very laggy, I was aiming at people and they'd disappear and pop up somewhere to the right or left depending which way they were moving, is that what you mean by frame drops? Also lots of black screen lock ups that would last a second or two and then return me to the action.
I switched it off and cleaned the ps3 vents and even made some little legs/stands so it sits a little higher and afterwards I returned and it was fine but I did return and play the old maps.