A quick look at the source tells me, that the most propable difference is the size used for reading and writing. File::Copy uses a buffer size of 2*1024*1024 bytes, while the programs written in C will most likely allocate a statically fixed buffer, whose size is not known.

As it seems, if your numbers and testing are correct, your harddisk/network stack/NFS combination handles large blocks better than small blocks (of, say, 64k).

perl -MHTTP::Daemon -MHTTP::Response -MLWP::Simple -e ' ;    # The  
$d = new HTTP::Daemon and fork and getprint $d->url and exit;#spider
($c = $d->accept())->get_request(); $c->send_response( new   #in the
HTTP::Response(200,$_,$_,qq(Just another Perl hacker\n))); ' #  web
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