It could be your MacBook is using the Intel GPU rather than the AMD GPU.
Also, do you know which video backend MAME is using? (D3D, OpenGL, BFGX) SHould be a setting in MAME64, you can try changing that.
If MAME64 has a logging/debugging option, turn that on and you should see which it is using. Using the standard command line version of MAME it's a simple -v option.