I'm assuming you're trying to get a list of which words are present in the text. substr is faster than regex for this, and lowercase searching is faster than case insensitive, so:

use strict;
use warnings;

my @bah = ( "Australia", "Austria", "Finland", "Norway" );
my $foo = "In Australia the people from Austria drink beer at the pub 
+with the people from Norway";
$foo = lc($foo);
my @f; for (@bah) { push @f, $_ if index($foo, lc($_)) != -1; }
print join(' ', sort @f), "\n";
[download]

I really don't think you're going to be able to get out of looping somewhere in the code, though.