Later versions of MAME prioritize extreme hardware documentation (accuracy), which requires much higher CPU power. Version 0.139u1 captures a sweet spot where over 8,000 games—including 90s hits like Street Fighter II and Mortal Kombat —run at full speed on dual-core processors.
A paper focused on this specific ROM set should explore why an "obsolete" version of software remains a benchmark for an entire industry (mobile retro gaming). Here are four potential angles: mame 0.139u1 roms list