Lazy val optimization for pure code

[sir-wabbit]

We could replace all lazy vals with the cheapest version of https://github.com/runarorama/latr (@Lazify) by default. If the code is pure, re-evaluating a thunk twice is not a problem and the probability of that happening is minuscule anyway.

See https://docs.scala-lang.org/sips/improved-lazy-val-initialization.html for more background