The Core Mame has a LAG frame compared to the official version. I did the test with several games, for example Mortal Kombat (Like most games) has intentional delay in their movements.
- Blow and kick in 4 frames in Mame, 5 frames in RA.
- Lock, move and bend in 3 frames in Mame, 4 frames in RA.
- Skip on 6 frames in Mame, 7 frames in RA.
The Mame Independent, I usually configure in the right joystick the gear lever for cars games (left -1 / down-2 / up-3 / right-4), to play them in manual, it is very comfortable. In Retroarch I can assign the option to the buttons in the control menu but do not work as expected. It seems that it was very close or several will be selected before touching a point, especially right. Try to configure the control in the MAME GUI but I can not get the menu with the control, I have to use keyboard and it does not work correctly.
Another thing I see, the shortcuts and buttons of Retroch and Mame are overlapped, all MAME should be deactivated.