emberjs/ember.js — pull request #3355 by ssured (2013-09-07 14:56:20+00:00)
Title: Added failing test for array computed observers

It seems in some cases array computed property observers fire for each change, instead of firing once for the full change. This can be a performance issue.

Sorry for not having a patch to fix this; the array computed implementation is quite hard to get my head around.