% perl -MList::MoreUtils=uniq -nwle 'END{ warn +(times)[0],"\n" }
  print $_ if /^(?:(.)(.)(.)(.)(.)$(?(?{ 5 != uniq $1, $2, $3, $4, $5 })(?!)))/
' /usr/share/dict/hv.words | wc -l
0.12
8632
%