bug#31138: Native json slower than json.el

[Dmitry Gutov]

On 23.04.2019 18:09, Eli Zaretskii wrote:

> If we want to make this more general-purpose, we should time the code
> with very long strings.  It could be that beyond some length the UTF-8
> verification, if it fails, will make the conversion slower, in which
> case we probably should not take the shortcut beyond that length
> limit.

If it fails, yes. Although it might still be an insignificant fraction 
of the total time it takes (verification is O(N), and conversion is O(N) 
as well).

> Or we might document that non-UTF-8 strings will be slower to convert,
> if that's acceptable.

*Invalid* UTF-8 strings. Strings that aren't actually UTF-8, even though 
the caller declares them to be.

I think this can be a good (and simple) tradeoff.