It is called a frame rate drop. You are not the only one with that problem. There are many player with good PC's that have it. It is the fault of the game itself, but the makers are doing something about it. Try pressing Alt+F when you are in-game, you should see the framerate in the bottom-left corner.
It is not framerate drop- I can still perform all actions (shooting, jumping, whatever), but the game is still in massive lag, like seeing vanguards dogfighting esfs while upside down.
I can run Eve AND Neverwinter AND have firefox going with a video running and no lag, I turn off everything except for Planetside 2 (have tried both via steam and a straight install) and within 10 minutes I start getting lag and flying tanks. Something somewhere is causing an issue on the Planetside server side, and has been for over a year. When the game first came out I could go a couple of hours no problem but the time I can play gets shorter and shorter. It is also not a problem with other SOE games as I have multiboxed EQ with no problems, just Planetside 2.