The CPU thing sounds like bullshit. They could renice your tasks just the same as anything else. I mean, Kareha pretty much caches everything out the ass already, updating things mostly just when the relevant pages have changed or not been updated since last change.

It's not like /cw/ or /moe/ got enough traffic for that to happen or anything. (Could there be a hidden processor time sink thing in Kareha, for boards that've got a bit older? I remember 4ch's DQN used to have a huge post delay before the long tail was archived.)