Although Capcom has optimized the code from Final Fight Guy compared to the previous release, they still didn't used FastROM addressing.
This conversion should remove every hint of slowdown.
Database match: Final Fight Guy (Japan)
Database: No-Intro: Super Nintendo Entertainment System (v. 20210222-050638)
File/ROM SHA-1: DB68F895D5872CFAC82D666FB342AF8C1A06E1FD
File/ROM CRC32: DE144411