>Yum has greately improved rpm management from the 90's, but is still, in my humble opinion, slower than apt, even when using deltas, fastermirror and such.
You could have a look at Suse for example, there it is faster while using delta rpms for the downloads, but while installing it too. So there is room for advancement, but I don't see huge differences with yum.
There are even enough alternatives compared to yum, like smart package manager.
http://labix.org/smart