Thanks VizualTek for your answer.
I created an empty level but the problem remains the same :
However, I created a brand new project, and think I localized the issue :
it’s in the sprites.
In my project I am using around 200 pictures, that I am presenting as paintings, through paper 2D sprites.
What is strange, is that the original .jpeg files are quite small, but once cooked by the editor, their size goes like 20 times bigger.
For instance, an asset freshly imported in the “Content” folder that weights 761ko goes to 18,6Mo (!!!) in the folder “Save/Cooked/MacNoEditor/…/Content/…”