I have the same, this is legit unplayable now. I started a flight yesterday, fps really good, as I start powering up and setting up the aircraft the fps drop. Once I started the engines and started taxiing the fps drop considerably, it's a massive stutter fest, you cant do much. I tried the external view which improved fps a bit but once back in the cockpit, back again to like 10 fps... from 50. Only with this plane, all my other addons work fine no issues.
Please fix this inibuilds, literally cannot fly with this anymore. I'm on the latest update for both 2024 and ini350.