Hi Paul,
I am not with Laminar Research; just a flight simmer.
Although X-plane has been or is being developed using a Mac system, Laminar Research staff have advised in this forum you will get better results with a windows based purpose built PC. You will need to "trawl" back some months to find the comment.
If you look down the RHS of your question as you read my answer you will find questions of the same nature. Have a look at the following link at https://questions.x-plane.com/8419/xplane-on-macbook-air?show=8420#a8420 In reading the comments in this link have a look at the comment about X-Plane for an iPad. This may help with the unit you have.
As X-plane is resource hungry it will generate heat. Good cooling is required. Some of the newer laptops on the market are built specifically for gaming with good cooling. They are quite thick in appearance and have some weight to accommodate the fans. What I have observed is a Mac system is quite thin and light
Good luck
Glenn