A couple of findings.
To avoid CTD when hit ALT or descend it helps adjusting altitude by only VS, during climb up, during cruise set VS to +0 feets per minute and descent down, it works.
I tried to downsize HD textures of Falcon (from 4096 to 1024), impact on FPS almost none.
When i hit SHIFT+A in first VC view there is default VC view, you know that, without cockpit instruments, a have nice 30fps.
In first VC view with cold n dark around 13 FPS! After powering up the instruments horrible 9 FPS.
Switching range in the middle MDU from default 20 miles to 3 miles FPS are quite better but not much. Seems helps also switch to INFO for airport for slightly better FPS
where the MDU is static. The gauges are too much hungry for FPS. I found some variables like refresh inside the CAB files as xml but not seen difference.