copy/paste in the shell, call Biggest(Milliseconds, N)

gistfile1.erl

F = fun() -> [{Pid, {Reds, Curr, Init}} || Pid <- processes(),
       {_, Reds} <- [process_info(Pid, reductions)],
       {_, Curr} <- [process_info(Pid, current_function)],
       {_, Init} <- [process_info(Pid, initial_call)]] end.

Fetch = fun(T) -> A = F(), timer:sleep(T), B= F(), {A,B} end.

Build = fun({A,B}) ->
  D = dict:from_list(A),
  lists:foldl(fun({Pid,{Red,Cur,Init}}, Dict) ->
    dict:update(Pid, fun({RedOld,_,_}) -> {Red-RedOld,Cur,Init} end, {Red,Cur,Init}, Dict)
  end, D, B)
end.

Biggest = fun(X,Y) -> lists:sublist(lists:usort(fun({_,{X,A1,A2}}, {_,{Y,B1,B2}}) -> X > Y end, dict:to_list(Build(Fetch(X)))),Y) end.