Hi Lucas,
Good news and bad news:
Good) NZCH is known to be extremely heavy on performance for an unknown reason. So it is not an issue with you sim/setup. Even on the highest power rigs it still drops to 10-20 FPS.
Bad) Orbx have decided that they are not going to bother updating it so we just have to live with it. Christchurch is my hometown but even I refuse to fly there in P3D because of the above issues.