bug#31138: Native json slower than json.el

[Dmitry Gutov <dgutov@yandex.ru>]

On 22.04.2019 15:07, Eli Zaretskii wrote:
> I don't know why.  In my profiles I enlarged the iteration count to
> 100, and also enlarged the sampling frequency.  Maybe that's the
> reason.

I posted my invocations here, with all arguments. I didn't see yours.

> The percentage taken by decode_coding_utf_8 didn't change as
> result, FWIW.

Maybe it's not the only bottleneck. What about produce_chars? And 
malloc, of course. Here's the top of my profiling report again:

  6.00%   229  emacs    emacs                 [.] decode_coding_utf_8
  5.31%   206  emacs    libc-2.27.so          [.] malloc
  4.57%   177  emacs    emacs                 [.] produce_chars
  4.12%   164  emacs    libc-2.27.so          [.] malloc_consolidate
  4.05%   161  emacs    libc-2.27.so          [.] cfree@GLIBC_2.2.5
  3.38%   135  emacs    libc-2.27.so    [.] __memmove_avx_unaligned_erms
  3.23%   125  emacs    emacs                 [.] store_symval_forwarding
  2.63%   102  emacs    emacs                 [.] do_symval_forwarding
  2.58%   104  emacs    libc-2.27.so          [.] _int_malloc
  2.58%   100  emacs    emacs                 [.] set_buffer_internal_2
  2.41%    93  emacs    emacs                 [.] allocate_vectorlike
  2.08%    81  emacs    emacs                 [.] json_to_lisp
  1.90%    81  emacs    emacs                 [.] detect_coding_utf_8
  1.85%    72  emacs    emacs           [.] swap_in_symval_forwarding
  1.72%    72  emacs    emacs                 [.] detect_coding
  1.38%    31  emacs    emacs                 [.] insert_from_gap
  1.29%    50  emacs    libjansson.so.4.11.0  [.] json_delete
  1.19%    46  emacs    emacs                 [.] hash_lookup
  1.01%    39  emacs    emacs                 [.] decode_coding
  1.01%    39  emacs    libjansson.so.4.11.0  [.] json_array_get