PicoDrive for 3DS is a port of notaz’s PicoDrive emulator by bubble2k16 to the old 3DS / 2DS. Although PicoDrive is already highly optimized for ARM processors, if ported as is, it still doesn’t run full speed for all Mega Drive games on the old 3DS / 2DS, as it’s evident in the RetroArch’s version. So this port heavily relies on the 3DS’s 2nd core to emulate the FM synthesized music for the YM2612 FM chip to achieve 60 FPS. But the 2nd core on the old 3DS is unfortunately not fast enough to generate the FM synthesized music at a full 44100Hz, so sounds are generated at 30000Hz on an Old 3DS. It sounds ok for many games, except for those that use high-pitched notes or sound samples. The screen rendering is done completely using the original PicoDrive’s ARM processor-optimized renderer.

You can play Master System, Mega Drive games and Sega CD games, and 32X games. CD games run a little slower (you should enable 1-2 frameskips) on an old 3DS, but it runs very well on a new 3DS. 32X games can only played at a reasonable speed on a New 3DS using the .CIA version of the emulator. Some dynarec instructions for 32X games will crash the emulator (Virtual Fighter, Virtual Racing Deluxe have this issue).