Chrome on my MBP really chugs trying to scroll down the page, I'm surprised it's being pushed that hard looking at the code.
There are other factors which can make scrolling less than butter smooth on slightly aged hardware, this seems to be a weak spot of many fancy designs. I don’t know whether those designs are just not tested in all browsers and on slightly older hardware or whether that’s an intentional trade-off. I’m extremely annoyed by even slightly jittery scrolling, but that’s probably just me.