Comparison of aggregating a sorted list in Erlang

sort-test.out

Erlang R16B02-basho5 (erts-5.10.3) [source] [64-bit] [smp:8:8] [async-threads:10] [kernel-poll:false]

Eshell V5.10.3  (abort with ^G)
1> sort_test:run().
Sort once at the end: 10266
 Sort after each append: 349
ok
2> sort_test:run().
Sort once at the end: 9724
 Sort after each append: 431
ok
3> sort_test:run().
Sort once at the end: 9407
 Sort after each append: 435
ok
4> sort_test:run().
Sort once at the end: 9740
 Sort after each append: 609
ok

sort_test.erl

-module(sort_test).

-compile(export_all).

run() ->
    Lists = [[{druuid:v4(), X} || X <- lists:seq(1, 30)] || _ <- lists:seq(1, 200)],
    {Res1, _} = timer:tc(ordsets, from_list, [lists:append(Lists)]),
    {Res2, _} = timer:tc(ordsets, from_list, [append_and_sort(Lists)]),
    io:format("Sort once at the end: ~p~n Sort after each append: ~p~n", [Res1, Res2]),
    ok.

append_and_sort(Lists) ->
    FoldFun =
        fun(L, Acc) ->
                lists:usort(Acc ++ L)
        end,
    lists:foldl(FoldFun, [], Lists).