Well I have come a lot lot further (hours and hours now!) - same plane and airport every single time.
It still doesn't look quite as nice as FSX (AA jaggies and a bit dark) but I have a very stable 26 fps - this was achieved by setting 26 p3d and wait for it.....26 in an external frame rate limiter (after editing batch file to change the 9 to 11 - not that I think the 11 does anything but I am sure it shouldn't be 9). The difference for me was huge. Also took off the limiter in Nvidia. More stutters at 30.
I also used these settings (taken from Airdailyx - I have 3 monitors with mth2go though plus the 26 fps limited as explained)
My scenery settings were tested 1 at a time and I found the best was to stagger them with the top one the highest (but 2 positions down) and each one 1 position lower successively.
I have shadows only in VC. I think I turned off most if not all lights.
Run full screen without the menu across the top.
Tessellation down in lower 1/3rd (big diff)
Clouds down to nothing at the moment.
Latest drivers and inspector.
Venetubo's tweaks unaltered and not Kosta's.
Obviously click the screen before taking off - jumps from 12 to 26 fps.
In Nvidia
- I found "enhance" was better and I am guessing from my testing the black screen is related mainly to this single setting outside of p3d (not that this solves it but changing it can invoke it more - perhaps that Nvidia issue they talk about on their forums?)
- SSGS 4 times
Also I had Aero disabled so I enabled that.
Still searching for better Nvidia settings, also I need to choose some setting in Nvidia panel itself but I forgot what it was. Anyone know?