Help with Metal Slug running slow

[EliasPR2309]

Hello, recently I have gotten into Recalbox and proposed myself to do an arcade box with it but the problem is that Metal Slug is running awfully slow, I don't remember it running so slow, it has gotten to the point where frame drops are common and the music gets shopped off, is there something I could do?

I already tried to overclock my Raspberry but there was next to no change, could the use of FBA2X fix the problem?

My setup is:
Raspberry pi 2
External memory
Xbox 360 controller
Libretro FBNeo

[barbudreadmon]

@eliaspr2309 https://github.com/libretro/FBNeo/tree/master/src/burner/libretro#game-xxx-runs-slowly-why-