LWP::Parallel::UserAgent faster than Parallel::ForkManager?

Hello everyone,
I was just curious how LWP::Parallel::UserAgent (LWP::PUA) compares 
against Parallel::ForkManager
in terms of speed.

For LWP::PUA, I have used what I think are optimal settings:

my $pua = LWP::Parallel::UserAgent->new();
$pua->in_order  (0);  # handle requests in order of registration
$pua->duplicates(0);  # ignore duplicates
$pua->timeout   (0);  # in seconds
$pua->redirect  (0);  # follow redirects

File Output was tested for both modules and only 8 urls were used for 
testing.
Parallel::ForkManager with LWP::Simple seemed to be slower than 
LWP::PUA by about 3 seconds.
Parallel::ForkManager with system("curl -s 'http://www.perl.com' > 
'perlcom.html'") seemed to be
slower than LWP::PUA by about 1 second.

...and now the questions:
Are 8 urls enough for Benchmarking purposes?
Does LWP::PUA use Forking or Threads?

Thanks in advance.


-gohaku