It doesn't help that the ag_6502 core they're using is designed to accurately reproduce the behavior of the original part, not to be space- or power-efficient.

It doesn't help that the ag_6502 core they're using is designed to accurately reproduce the behavior of the original part, not to be space- or power-efficient. Results might have been better with a more modern CPU design like SERV (https://github.com/olofk/serv https://github.com/olofk/serv).