We have moved this topic to the User Support Hub > Install, Performance & Graphics category as users have been utilising this thread to help troubleshoot.
If you believe your issue may be related to the following bug, please ensure you report it in the already existing forum thread: Mainthread loads up more and more and doesn’t recover - Sim Update 3 Beta | MSFS 2024 / Install, Performance & Graphics - Microsoft Flight Simulator Forums
Thanks
The MSFS Team