Hi, I don't understand everything you're talking about, so my answer will perhaps be off-topic.
If you want to win FPS, the easier way is to reduce mirors quality (just one step and you'll go around 10% faster) .
FPs is a often discussed subject. aS FBS is a simulator using "Unreal Engine", you cannot have allways 60FPS. Low FPS is common with simulators, because ou have a lot of parameters to handle. And FBS has beautifull graphics, so this a reason to have lower FPS.
My personnal opinion is that too many are just looking for many FPS. What's the real difference between 60 and 40 FPS ? I learned that human eyes are ok with 25 ips, which are used with movies. I'm flying with MSFS and be also satisfied with only 15-20FPS....