Hi again
I have looked at your Log.txt file and have noticed that your are using a Steam variant of X-Plane 11 and on that basis, you should be referring this matter to them!
However, leaving that aside, I have the following observations:-
1. Your MacBook Pro has an 8th generation 6 core Intel(R) Core(TM) i7-8750H CPU running @ 2.20GHz CPU speed. As you will see from Laminar Research's website, the minimum CPU specification is 3.0GHz, with the recommended being 3.5GHz!. Please see following link:
https://www.x-plane.com/kb/x-plane-11-system-requirements/. There may therefore be a bottleneck here?
2. In terms of graphics, your MacBook has an AMD Radeon Pro 555X card running 4GB of GDDR5 memory, with DirectX 12 support. This should be OK, but is however at the minimum end of the recommended specification.
3. RAM memory @ 16GB is more than sufficient.
4. The final entries in your Log.txt file are as follows:-
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
Mem file error. Err=22, file=/Users/avio/Library/Application Support/Steam/steamapps/common/X-Plane 11/
I would therefore suggest that you use some third party software to 'stress test' your MacBook, just to see if any issues are highlighted?
If you go to
https://cpu.userbenchmark.com/Software, you can download a small piece of software to test your whole PC.
If you go to
https://www.memtest86.com/ and again download a small piece of software, it will test and analyse the RAM memory in your MacBook.
Try these first to see how you get on!
Regards