I hope my example code here explains the problem. I need to do what this code does, but I need to do it faster. In my example there are only a few strings and a few hash keys to match again. In my real case there are millions of strings and a few thousand hash keys. Obviously this approach scales horribly. How can I make it fast? Thanks in advance. 

my @strings = (
    'Some string about this long or so, maybe this long',
    'I like pizza this long or so, maybe this long',
    'this long or so, maybe this French Fries long',
    'This Sugar Rush Rocks. maybe this do not stop the clock.',
);

my %hash = (
    'Sugar Rush Rocks' => 'whatever',
    'long' => 'itsgood',
    'this long' => 'ilikeit',
    'maybe this' => 'itsokay',
    'Some String' => 'loooveit'
);

my @keys_sorted_by_length_desc  = sort { length $b <=> length $a } key
+s %hash;

foreach my $string (@strings) {

    foreach my $key (@keys_sorted_by_length_desc) {
        my $key_re = quotemeta($key);

        if ($string =~ /(:?\A|\s)($key_re)\s*/i) {
            print "Found '$key' in '$string'\n";
            last;
        }

    }

}

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In reply to Matching Many Strings against a Large List of Hash Keys (case insensitively, longest key first) by Anonymous Monk

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