...
our $M //= 16; ${^RE_TRIE_MAXBUF} = 2**$M;
...
__END__
C:\test>for /l %i in (18,1,32) do
    @\perl5.18\bin\perl.exe -s 1043602.pl -M=%i C:\docs\OriginOfSpecies(Darwin)\2009-h\2009-h.htm
Finding 203474 words (of 216808) took 0.175862 seconds using a hash
201     Finding 203474 words (of 216808) took 0.174275 seconds using a hash
249     Finding 203474 words (of 216808) took 0.173872 seconds using a hash
174     Finding 203474 words (of 216808) took 0.174906 seconds using a hash
201     Finding 203474 words (of 216808) took 0.175149 seconds using a hash
205     Finding 203474 words (of 216808) took 0.172946 seconds using a hash
183     Finding 203474 words (of 216808) took 0.176250 seconds using a hash
196     Finding 203474 words (of 216808) took 0.175480 seconds using a hash
201     Finding 203474 words (of 216808) took 0.174416 seconds using a hash
196     Finding 203474 words (of 216808) took 0.179129 seconds using a hash
210     Finding 203474 words (of 216808) took 0.174478 seconds using a hash
197     Finding 203474 words (of 216808) took 0.174674 seconds using a hash
183     Finding 203474 words (of 216808) took 0.177501 seconds using a hash
225     Finding 203474 words (of 216808) took 0.174395 seconds using a hash
197     Finding 203474 words (of 216808) took 0.178181 seconds using a hash
221
C:\test>