WORD:
foreach $word (@data)
{
   STOP:
   foreach $stop (@stopwords)
   {
      next WORD if $word eq $stop; # <---
   }

   push(@lessWords, $word);
}

##</code><code>##

my %stops = map {$_,undef} @stopwords;

for my $word (@data)
{
    next if exists $stops{$word};
    push(@lessWords, $word);
}