The bright side of this push to get things running well on the nexus 7 is that these inefficiencies will have to be dealt with. I'm running this build the Nexus7 now and, yeah its slow, but as the goal for 13.04 is getting the performance and battery life acceptable, these developments 'should' leak back and help the whole Ubuntu experience. It might just be the itch required to get development focused on performance again.