You can install Gtk2 on win32 fairly easily with Camelbox: A build of Gtk2-Perl for Windows. Then you can do this.

#!/usr/bin/perl
use warnings;
use strict;
use Gtk2 -init;
use Time::HiRes qw( time );

my $time_start = time;

my $s = Gtk2::Gdk::Screen->get_default;
my $w = $s->get_root_window;

# pixbuf = $pixbuf->get_from_drawable ($src, $cmap, $src_x, $src_y,
#                                    $dest_x, $dest_y, $width, $height
+)

while (1){
my $p = Gtk2::Gdk::Pixbuf->get_from_drawable (
            $w, undef, 0, 0, 0, 0, $s->get_width, $s->get_height);

$p->save (time.'.png', "png");

}

my $time_end = time;
my $diff = $time_end - $time_start;
print "$diff\n";
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