For the serial code, it knocks about 6 seconds off for me (1m13 vs 1m19 - 2GHz MacBook) if I use a un-named ETS table, i.e.
table = :ets.new(:words, [])
and then use the reference directly instead of the name:
|> Enum.each(fn word -> :ets.update_counter(table, word, {2, 1}, {word, 0}) end)
etc.
This makes sense since now ETS doesn’t have to be concerned about concurrency at all, and there’s no lookup for the table by name.
Of course, now you can’t take advantage of concurrency 
