Because 0.139u1 is a heavier, more accurate emulator than older mobile versions (like MAME4all), some highly demanding 3D arcade games from the late 90s might lag on older or budget Android hardware. Sticking to 2D classics yields the best performance. Disclaimer:

This article dives deep into the history, technical specs, setup guide, and legal landscape surrounding this specific emulator build and its required ROM set.