Thank you,
Ok, with the 0.39 update I switched to a better rendering system which has a higher cost and forces me to use Metal on MacOs.
I tried this build on a MacBook Air, and it works, slowly...
By the way, I work on Mac, so the game runs on MacOs and it's my first build target :)
So maybe it's High Sierra and Metal, maybe the GPU... I'll keep investigating that.
I'm working on improving all of this, and I'll release an update as soon as I can.
Thanks again for the feedback, and thank you for your interest in the game!