For what its worth, I kicked out the A-4 Community Mod and the Military Aircraft Mod (MAM), the latter I was using some of the units of in the mission I had been flying for a while now, and was using as my 'benchmark'. Without these mods installed, I re-gained most if not all my fps - in VR, so hard to give exact numbers, but its smooth again.
As I reported earlier in the thread, I couldnt keep 45 fps after the update at Nellis for example, on the runway facing north. Had no problems with that before. But also when looking around while airborne, I would get really bad stutters, even with 45 fps. All this corrected itself with the above mentioned Mods uninstalled. Cant say if it was both or just one of them, or maybe just one of the planes in MAM.