parse_form_outer(eof, _, Acc) ->
    lists:reverse(Acc);
parse_form_outer({headers, H}, FileHandler, State) ->
    {"form-data", H1} = proplists:get_value("content-disposition", H),
    Name = proplists:get_value("name", H1),
    Filename = proplists:get_value("filename", H1),
    case Filename of
        undefined ->
            fun (Next) ->
                    parse_form_value(Next, {Name, []}, FileHandler, State)
            end;
        _ ->
            ContentType = proplists:get_value("content-type", H),
            Handler = FileHandler(Filename, ContentType),
            fun (Next) ->
                    parse_form_file(Next, {Name, Handler}, FileHandler, State)
            end
    end.

%%% 18> proplists:lookup(loop,[{ip, "127.0.0.1"},{loop, {mochiweb_http, default_body}}]).
%%%   {loop,{mochiweb_http,default_body}}

parse_options(Options) ->
    {loop, HttpLoop} = proplists:lookup(loop, Options),
    Loop = fun (S) ->
                   ?MODULE:loop(S, HttpLoop)
           end,
    Options1 = [{loop, Loop} | proplists:delete(loop, Options)],
    mochilists:set_defaults(?DEFAULTS, Options1).

-module(pvsl).
-define(LIST_SIZES, [10000, 100000, 1000000]).
-define(RETRIES, 1000).
-compile(export_all).

start() ->
        % test for different list sizes
        lists:foreach(fun(N) -> test_list(N) end, ?LIST_SIZES).

test_list(ListSize) ->
        % generate a list of size ListSize of {Key, Val} entries
        KeyList = [{K, K} || K <- lists:seq(1, ListSize)],
        % test this list against both functions
        lists:foreach(fun(Type) -> get_val(Type, now(), KeyList, ListSize, ?RETRIES) end,
                [proplists, lists]).

% test getting values, compute necessary time and output print results
get_val(Type, Start, _KeyList, ListSize, 0) ->
        T = timer:now_diff(now(), Start),
        io:format("computed ~p random key searches on a ~p-sized list in ~p ms using ~p~n",
                [?RETRIES, ListSize, T/1000, Type]);
get_val(proplists, Start, KeyList, ListSize, Tries) ->
        proplists:get_value(random:uniform(ListSize), KeyList),
        get_val(proplists, Start, KeyList, ListSize, Tries - 1);
get_val(lists, Start, KeyList, ListSize, Tries) ->
        lists:keyfind(random:uniform(ListSize), 1, KeyList),
        get_val(lists, Start, KeyList, ListSize, Tries - 1).

I ran this test on my MacBook Pro, Intel Core i5 2.4GHz with 4GB Memory, and Erlang R13B04, with Kernel Polling enabled. These are the results.
roberto$ erl +K true +P 1000000
Erlang R13B04 (erts-5.7.5) [source] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:true]

Eshell V5.7.5  (abort with ^G)
1> c(pvsl).
{ok,pvsl}
2> pvsl:start().
computed 1000 random key searches on a 10000-sized list in 323.373 ms using proplists
computed 1000 random key searches on a 10000-sized list in 12.897 ms using lists
computed 1000 random key searches on a 100000-sized list in 3273.973 ms using proplists
computed 1000 random key searches on a 100000-sized list in 130.592 ms using lists
computed 1000 random key searches on a 1000000-sized list in 34131.905 ms using proplists
computed 1000 random key searches on a 1000000-sized list in 2050.627 ms using lists
ok
3>