* Rakudo -- the only P6 compiler for now (and likely many years, maybe forever) -- has a slow startup, around 0.1 seconds or so.
* Rakudo is still a work in progress. What's done is pretty solid but, for example, no one has implemented the `-a` awk/autosplit command line option (cf https://gist.github.com/raiph/1d0cbefcb3cfe45b0b906282e6e405...) and command line usage is currently `use strict;` by default so you have to declare variables with `my`.