My coworker and I had a good time with this kata.
After finishing it I created a corollary. Find the longest word chain. For example, the longest word chain for all three letter words is [asp ask ark are abe aye rye rae ray say sky ski sri uri uzi]. That took 210 milliseconds to find.
I highly recommend trying the corollary.
My longest time are for the 8 letter words. The chain is 30 words long and it takes 991 milliseconds to find.