The layout can be tightened up a little bit. I experience no significant lag when scrolling or changing feeds. Imo, the blogosphere is overreacting. I disliked the look and feel of the old one :)
Second parent, I don't agree with the article either. Real world engineering is not pure theory. It is a subtle difference. A perfectly valid reason for this type of problems is "it works well in practice", or "it is good enough".