Workaround.
Start the mcdu server.
Go to → community → flybywire-aircraft-a320-neo → MCDU SERVER
Double click server.exe
press N or Y key → press enter key.
No need to open the remote fmc on another device.
https://forums.flightsimulator.com/t/pc-sim-update-8-stutter-with-addons/501913/155