MACOS - Game runs better with CPU than GPU ? very low fps - How to increase performances ?

Hi,

I developed a 2.5D metroidvania styled game,

It run smoothly on my powerful Windows computer (120fps in 4K), as expected.
But on my mac laptop (i7, 750m) it run very very low, around 8fps.

I have a big job todo on increasing overall performances and optimisation, but even then, it seems that my game wont be able to run on any mac os device.

**IMPORTANT : Then I deactivated my GPU, and force the game to use only the CPU -> And so the game run with 12FPS with the CPU ONLY ! 4 fps more that if I use the GPU …
**

How this is even possible that the game runs better with the Processor than the GPU ?

I’m new to UE4, If your have any advices on the matter, thanks for the help !

Please, This is a serious issue for me, can somebody help me ?