Off Topic: "Laying out icons on a grid should be an inherently linear operation"

it doesn't seem mentioned in the HN thread the cause here is probably the same thing O(n^2): sorting. laying out icons is only linear if the icons are read in the order that they're placed. It's been a long time since I used windows regularly but my memory is the default placement is by creation time. So if they're read off disk by filename (or some sort of hash) they'd need to be sorted by timestamp.