bart,
I have found cases where no matter how good you made the RE, if there were a lot of things to match and the data to match on was also large - it was never faster than matching each piece individually. I offer this alternative - which uses your suggestions.

#!/usr/bin/perl -w
use strict;

my %temphash = ( 't[0-3]om' => "good", "dick" => "bad", "hary" => "ugl
+y" );
my $temp = 'This is a string containing t[0-3]om and dick';

my @results = map {my $var = quotemeta $_;$temp =~ /\b($var)\b/} keys 
+%temphash;

print "$_ matched\n" foreach(@results);
[download]

In this very small example, I do not know if this method would be faster - but hey - it is nice to have in the tool box.

Cheers - L~R

Update: See this for an example of how to combine this method with a sub to make the process even faster if you have to reuse it.