[O] Experiences with "literate elisp" and ob-tangle?

[John Wiegley]

Hi all, I'm considering switching my lengthy .emacs over to a literate Org
file, using ob-tangle, and as I was wondering if others had any experience
with this, and if so, does it slow down startup much?  Is there a way to get
ob-tangle to compile the resulting Elisp file?  I'm guessing it does not
regenerate the .el file if no changes have been made to the .org, right?

Thanks,
  John