James Brown on Nostr: If the lines were completely independent, you could evenly scan a sector with half ...

If the lines were completely independent, you could evenly scan a sector with half the number of line updates compared to updating the whole frame. As it is, each line has to be updated in parallel with one that's half a panel further down, so it ends up taking 3/4 of the line updates instead (because some updates have to update the outer line while scanning out black to the inner line).