I think you can just do:

  (setq comp-speed 3)

Then you should tell it to recompile all of your elisp files:

  (native-compile-async "~/.emacs.d/elpa/" <n> t)
  (native-compile-async "<path/to/system/elisp/files>" <n> t)

Where <n> is the number of threads you want. It's also possible than you have deferred compilation and that's the problem?

try this: https://github.com/daviderestivo/homebrew-emacs-head