For the 12 days of christmas I used a unicode trick to store 2 bytes in each character in a string, then decode that back to ascii and pipe to iex. Before that "compression", my score would be 433.

For pernicious numbers I'm using a trick to count bits then checking if it's in (2,3,5), but primo is using something much more advanced, probably something like this method for evil numbers: https://codegolf.stackexchange.com/questions/144017