It's a bit complicated to comment on DS vs. N64.
DS games generally look way better than N64 games when upscaled but natively they ran at a lower resolution (192p vs. 240p). Though the N64 CPU was, on paper, some 50% faster than the DS's, that would've meant it was faster than a Pentium while the opposite was true and it was not even close.
I think the DS was deliberately designed to be a portable N64, so there's that to consider.