If you were suggesting that we implement reading JSON objects as part
of Emacs, then yes, this won't need to encode/decode anything.  I'm
not sure the result will be as fast as read-from-string, since we are
talking about a different syntax.  Also, I'm not sure how hard would
that be nor how much maintenance will it require (does the JSON spec
change frequently?).  But if someone knows the answers, perhaps it's
an alternative worth considering.