It was never so bad that I actually noticed untill tonight, being cut from 45 to 10 fps in VR then from 70+ to 10 or less in flat mode on Persian Gulf.. in Caucasus it only brought me down to 30 after some tweaking.
Edit: I tracked down the cause of this issue to being the exportscripts mod, the AH64 LUA has some broken code in it and can be rectified by deleting function lines within. Here is the link to the relevant post in September :
Hope this helps anyone still having the issue 🙂
Skyrage's post in multiplayer FPS drops when turning on CMWS was marked as the answer