oleguerinsano
as voljega said, desmume is a very hardware demanding emulator.
for RPi (2 and 3) the Nintendo DS Emulator DraStic would be better (good performance even with RPi2).
but unfortunately DraStic is not open source and so it can/will not be used in Batocera.
the deveolper of DraStic mentioned a while ago, that he is planning to make the emulator open source, but this did not happen yet.
