This code problem is nothing we can do. You need access to source code and rewrite some mechanics to work multi thread there. I also can´t say, if this is common for godot engine based games or if this could be fixed in game coding part. Normaly it should be fixed in game coding, but its´s more then to change a trigger. You need to learn first the mechanic and syntax of multithreading in godot.
https://docs.godotengine.org/en/3.1/tutorials/threads/using_multiple_threads.htm...
There is also some special in the conservation between multiply threads, so it´s also some more work to wait (sleep) in one thread till the other thread is finished. This is something we can´t do. You can only try to speed up your system or try to find a way to stop a shutdown.
https://www.howtogeek.com/183004/why-android-phones-slow-down-over-time-and-how-...