Frame rate fluctuation

Ver 1.0.1.1. P3DV4 I wanted to raise the issue of fluctuating frame rates again in the latest builds. My comp is a mid-range I7-3770K, GTX980, 16GB RAM. The settings are upper-high in sim. 2XSSAA. The frame rates on average are high in spot view but they fluctuate wildly between say 100 and then every few seconds down to 20 then up again (similarly between 40 and 20 in VC view). This makes for stuttering which makes it difficult to obtain smoothness especially

I have an older system but have it tuned nicely. My graphics are pretty plain looking, but I'm in it for the systems simulations, not the pretty trees on the ground. I'm running FSX:MS and have a 2600K running at 4.6GHz, nVidia 560Ti, 16GB RAM, etc. I know my system is old. However, I have all the highly complex addons and never have stutters. I get low FPS primarily with the FSL A320, but even when FPS drop into the teens, I'm still not having stutter issues there. When in spot mode in the CRJ,