Communication performance difference between denops v5 and v6

To find performance improvement from denops v5 to denops v6, operations per milliseconds (OPMS) has measured with denops-benchmark.vim on the following environment.

Key	Value
OS	macOS Sonoma 14.2.1
CPU	Apple M1 Max
Memory	64 GB
Vim	9.1
Neovim	0.9.5
Alacritty	0.13.0 (78fa3d6)

Results

denops.call()

	Vim (v5)	Neovim (v5)	Vim (v6)	Neovim (v6)
Average	7.6	8	8.2	8.8
Stderr	0	0.1	0	0

Approx. x1.08 improvement is observed for Vim and x1.10 improvement is observed for Neovim.

denops.batch()

	Vim (v5)	Neovim (v5)	Vim (v6)	Neovim (v6)
Average	218.1	458.7	265.3	824.6
Stderr	1.3	5.5	1.5	8.9

Approx. x1.21 improvement is observed for Vim and x1.80 improvement is observed for Neovim.

Details

v5

Vim

info
  size:   64 bytes
  count:  1000
  n:      100
denops.call()
  sum:     13177 ms
  mean:    131.8 ms
  median:  128.7 ms
  stddev:  11.3
  stderr:  1.1 ms
  opms:    7.6±0.0 ops/ms
  cpms:    488.4±3.2 chars/ms
denops.batch()
  sum:     461 ms
  mean:    4.6 ms
  median:  4.5 ms
  stddev:  0.4
  stderr:  0.0 ms
  opms:    218.1±1.3 ops/ms
  cpms:    13959.0±80.4 chars/ms

Neovim

info
  size:   64 bytes
  count:  1000
  n:      100
denops.call()
  sum:     12637 ms
  mean:    126.4 ms
  median:  122.4 ms
  stddev:  10.2
  stderr:  1.0 ms
  opms:    8.0±0.1 ops/ms
  cpms:    509.0±3.2 chars/ms
denops.batch()
  sum:     225 ms
  mean:    2.3 ms
  median:  2.1 ms
  stddev:  0.7
  stderr:  0.1 ms
  opms:    458.7±5.5 ops/ms
  cpms:    29355.5±350.3 chars/ms

v6

Vim

info
  size:   64 bytes
  count:  1000
  n:      100
denops.call()
  sum:     12189 ms
  mean:    121.9 ms
  median:  120.3 ms
  stddev:  5.8
  stderr:  0.6 ms
  opms:    8.2±0.0 ops/ms
  cpms:    526.2±2.3 chars/ms
denops.batch()
  sum:     379 ms
  mean:    3.8 ms
  median:  3.7 ms
  stddev:  0.3
  stderr:  0.0 ms
  opms:    265.3±1.5 ops/ms
  cpms:    16980.4±98.2 chars/ms

Neovim

info
  size:   64 bytes
  count:  1000
  n:      100
denops.call()
  sum:     11342 ms
  mean:    113.4 ms
  median:  111.5 ms
  stddev:  6.9
  stderr:  0.7 ms
  opms:    8.8±0.0 ops/ms
  cpms:    566.1±3.0 chars/ms
denops.batch()
  sum:     124 ms
  mean:    1.2 ms
  median:  1.2 ms
  stddev:  0.3
  stderr:  0.0 ms
  opms:    824.6±8.9 ops/ms
  cpms:    52774.0±570.2 chars/ms