Thank you for this detailed explanation! Very interesting. I also noticed that when I am flying Planes with glass cockpit, the frames go down by around 20 FPS, which makes sense since it is more work for the CPU. However I havent had this effect prior to SU3. Like literally the second I switch on the screens, the stutter party begins.
So I am wondering if it is a problem with the glass panels, the environment or a combination of both.