Dup/Select/Uniq  11.380000   0.100000  11.480000 ( 11.517070)
Group_By          0.020000   0.000000   0.020000 (  0.014287)
----------------------------------------- total: 11.500000sec

require 'rubygems'
require 'active_support'
Foo = Struct.new(:id, :status_id, :profile_id)
...

grouped = [] 
arr = [#<Foo id: 1, status_id: 2, profile_id: 3>,#<Foo id: 2, status_id: 2, profile_id: 3>,#<Foo id: 3, status_id: 1, profile_id: 3>]
arr_copy = arr
...