Absolutely. Package managers are mostly IO-bound so there is no reason why a Python-based PM should be substantially slower than a C implementation.

Except when they are calculating dependencies

But I agree with the yum sentiment, it really looks bad when compared to other solutions that existed: urpmi, apt-rpm, etc

Yeah, i've always found that quite odd. Do you seriously need to refresh the package db every. single. time? I might agree that cron-based/user-initiated solutions are suboptimal (some users will just not bother, which is a security and support problem), but surely there is a compromise, like limiting the refresh to once a week.

(Cue some RedHat fanboi saying "but it's easy, you just do xyz" -- no, it's not easy unless it's default behaviour. Otherwise we might as well just run OpenBSD, because opening network ports every time you have to sneeze is "so easy".)