MacOS – shortcut to expand all folders in Finder’s list view

The window may be using one of the "Arrange By" options. Disclosure triangles are not available in "arranged" views. If that's the case, you can choose View → Arrange By → None or press ^ control⌘ command0.

On Mojave the concept is called "Group" instead of "Arrange". Keyboard shortcut is the same. Menu item is found as follows: View → Use Groups.

I have not observed Lion to be faster at calculating folder (and package/bundle) sizes during the first time it calculates sizes in a folder. However, subsequent calculations in the same folder do seem to be much faster.

Part of the perceived quickness may be that Finder will immediately show the previously calculated sizes in gray text while it recalculates folder sizes, rather than showing "--" until it's been calculated. After a folder's size has been recalculated, the number will update (if the size has changed) and turn black.

Because the Finder is observably caching previously calculated folder sizes, it's possible that it's only recalculating sizes for folders that have changed since the last time it was calculated.