Perhaps I'm misunderstanding the question, but it seems to me that AlfaProject has a CGI script written in Perl and has specifically asked if using Perl to open a file (and use LWP) is 'faster' than using unix commands to achieve the same thing. From what I read from your reply you seem to think that they asked a more general question, sort of like the post title, 'which is faster bsah or perl in CGI scripts'.

Benchmarking the script will determine which is 'faster', performance testing a application/interface is different from benchmarking, as you suggest.

Obviously there are other things to take into account, some of which would require much more detailed information in order to advise properly.