If the purpose is to do it fast, why the sleep? Anyways, the following lines of your code:

foreach $arg (@ARGV) { $string = $string . "+" . "$arg" } # parsing ha
+ck
$string =~ s/^\+//g; # hack to hack the parsing hack
[download]

..are better and more succintly put as merely $string = join '+', @ARGV

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^+*`^ ve^#$&V"+@( NO CARRIER'