A patch (1.15.10.0) addressing the multiplayer stuttering issue is now available for Microsoft Flight Simulator in the Microsoft Store and on Steam. Full patch notes can be found here:

- Framerate stuttering when custom liveries are being used in multiplayer has been fixed
- Update to live weather system to improve accuracy globally

You only have to download the new .exe (from Steam or Microsoft Store), no package to download. The launcher update is approximately 1 GB on the MS Store and ~237MB on Steam.