woz$ perlbrew use 5.18.0
woz$ time perl re.pl 

real	0m0.035s
user	0m0.026s
sys	0m0.004s
woz$ perlbrew use 5.20.0
woz$ time perl re.pl 

real	0m0.128s
user	0m0.120s
sys	0m0.005s