Hello everyone,
I also had this problem for a long time (FPS around 40-50 when I was not moving and stutter when I was moving the camera) and nothing I found on the net solved my problem (turn off Traffic, turn off NDU etc), until I decided to completely uninstall my Nvidia drivers with the DDU software.
I then reinstalled them then launched MSFS and miraculously I had no more stutter… until I restarted Nvidia Geforce experience and then the stutter came back…
So it was Nvidia Geforce experience that was causing the problem for me.
I reinstalled the drivers again properly WITHOUT GEFORCE EXPERIENCE and the stutter have now completely disappeared. I wanted to share this trick because I searched, searched, searched for a long time so if it can help someone 
I always thought that Nvidia Geforce experience was ■■■■, now I have proof of it and I wouldn’t install it anymore.
GOUJE#3092
EDIT 17/08/2022 :
It worked all day yesterday, restarting the game several times and it was working fine…
Today, i relaunch MSFS (without reboot my computer) It doesn’t work anymore…
Now, to avoid stuttering, I have to reinstall the drivers and the stuttering disappears. If I restart the game a second time, the stuttering starts again… I don’t understand anything… I’m tired… I spent the whole day looking for why… If I want to play correctly now, I have to reinstall my graphic drivers each time I launch MSFS.