The Optimized sets often remove the PIC chip simulation data entirely, because Supermodel uses a HLE (High Level Emulation) hack to bypass the security. Does that affect gameplay? For 99% of games, no. But for Virtua Fighter 3: Team Battle , the optimized set sometimes causes a softlock during intro sequences that the raw MAME set avoids.
Beyond the files themselves, "better" performance often depends on how the emulator interacts with the romset: supermodel romset better
: Use recent main ROMs (split or non-merged). Merged sets are often missing files required by Supermodel, such as the segabill device ROM, which must sometimes be manually added to game ZIP files. The Optimized sets often remove the PIC chip