For those of you wondering why tekezo has ported another NES emu to the DC, he has explained it in this topic on the NesterDC forums:

“NesterDC get to limitation of speed and stability due to written by C++.
I think only I do for NesterDC is functional update now. That’s why.

I’ll test speedup hacking on FCE Ultra, and take feedback to NesterDC.
(current-NesterDC already use FCE Ultra knowhows).”