You're iterating through the wordlist too many times, giving you O(N**2) scaling, or worse. Try making your wordlist the keys to a hash, which will speed lookups a lot. Something like this,

my %word;
{
    open my $fh, '<', '/path/to/wordlist.txt' or die $!;
    chomp( my @words = <$fh>);
    close $fh or die $!;
    @word{@words} = ();
}
# ... then when it's time to look up a word,
    if (exists $word{$foo}) {
        # ...
    }
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