Neither will use enough to matter. I can make a case both ways and would be that it varies more between servers than it does between cases. POST sends a little more data but putting the data in a header eases the burden of parsing the data. POST creates a buffer for the STDIN pipe but GET burdens the Environment of the shell.

My advice? Spare your users the ugly URLs and use POST. If that advice falls on deaf ears, then I recommend you use the one you are more comfortable with. Your time is more valuable than 10 times the server resources you would ever save.

And if you use Perl, for goodness sakes use CGI; is your friend. Then you can use either and it will work just the same. (well, unless you move more than 8 or 16 KB of data or need file uploads, then POST is your only rational choice.)

--
$you = new YOU;
honk() if $you->love(perl)