@Foul even 68060 is slow on C-based emulators like MAME
The DS has a more powerful CPU, and MAME has not been ported. Instead there's MarcaDS with (I think) recode of the CPU emulation stuff directly in assembly.
Without a gfx board video is sloooow since the principle of MAME is chunky pixels so even with a fast C2P it's not smooth...
It costs a lot of CPU to mix sounds too SDL-like.
I tried to run MAME on 68060 several years ago (using a GFX board) and I was very disappointed by the speed/refresh rate, even with games like PacMan!