Neovimの文字入力とカーソル移動を計測したら、改善点は別にあった

-- Neovimの設定を読み込んだ後のキー処理時間を測る。
-- タイピング速度や、キー入力から画面描画までの時間は測らない。

local N = 2000
local warmup = 100
local uv = vim.uv or vim.loop

local function now()
  return uv.hrtime()
end

local function percentile(values, p)
  local sorted = vim.deepcopy(values)
  table.sort(sorted)
  local index = math.max(1, math.ceil(#sorted * p))
  return sorted[index]
end

local function summarize(values)
  local total = 0
  local max_value = 0
  for _, value in ipairs(values) do
    total = total + value
    max_value = math.max(max_value, value)
  end
  return {
    count = #values,
    median_us = percentile(values, 0.50) / 1000,
    p95_us = percentile(values, 0.95) / 1000,
    p99_us = percentile(values, 0.99) / 1000,
    max_us = max_value / 1000,
    total_ms = total / 1000000,
  }
end

local function feed(keys)
  vim.api.nvim_feedkeys(keys, "xt", false)
  if vim.env.NVIM_BENCH_REDRAW == "1" then
    vim.cmd("redraw")
  end
end

local function assert_state(condition, message)
  if not condition then
    error("BENCH_ASSERTION_FAILED: " .. message)
  end
end

local function set_lines(lines)
  vim.cmd("stopinsert")
  vim.api.nvim_buf_set_lines(0, 0, -1, false, lines)
  vim.api.nvim_win_set_cursor(0, { 1, 0 })
end

local function benchmark_char_input()
  set_lines({ "" })
  local input_cycle = vim.keycode("ix<Esc>")
  for _ = 1, warmup do
    feed(input_cycle)
  end

  local values = {}
  for i = 1, N do
    local start = now()
    feed(input_cycle)
    values[i] = now() - start
  end
  local length = vim.api.nvim_buf_get_lines(0, 0, 1, false)[1]:len()
  assert_state(length == warmup + N, "char_input length=" .. length)
  return summarize(values), "chars=" .. length
end

local function benchmark_line_motion()
  local lines = {}
  for i = 1, N + warmup + 20 do
    lines[i] = string.format("line %05d: 0123456789", i)
  end
  set_lines(lines)
  feed("gg")
  for _ = 1, warmup do
    feed("j")
  end

  local values = {}
  for i = 1, N do
    local start = now()
    feed("j")
    values[i] = now() - start
  end
  local line = vim.api.nvim_win_get_cursor(0)[1]
  assert_state(line == warmup + N + 1, "line_j line=" .. line)
  return summarize(values), "line=" .. line
end

local function benchmark_word_motion()
  local words = {}
  for i = 1, N + warmup + 20 do
    words[i] = string.format("word%05d", i)
  end
  set_lines({ table.concat(words, " ") })
  feed("0")
  for _ = 1, warmup do
    feed("w")
  end

  local values = {}
  for i = 1, N do
    local start = now()
    feed("w")
    values[i] = now() - start
  end
  local column = vim.api.nvim_win_get_cursor(0)[2]
  local expected_column = (warmup + N) * #("word00001 ")
  assert_state(column == expected_column, "word_w column=" .. column)
  return summarize(values), "column=" .. column
end

local function benchmark_search_motion()
  local lines = {}
  for i = 1, N + warmup + 20 do
    lines[i] = string.format("needle %05d", i)
  end
  set_lines(lines)
  vim.cmd("silent! keepjumps 1,1/needle/")
  for _ = 1, warmup do
    vim.cmd("silent! normal! n")
    if vim.env.NVIM_BENCH_REDRAW == "1" then
      vim.cmd("redraw")
    end
  end

  local values = {}
  for i = 1, N do
    local start = now()
    vim.cmd("silent! normal! n")
    if vim.env.NVIM_BENCH_REDRAW == "1" then
      vim.cmd("redraw")
    end
    values[i] = now() - start
  end
  local line = vim.api.nvim_win_get_cursor(0)[1]
  local expected_line = warmup + N + 2
  assert_state(line == expected_line, "search_n line=" .. line)
  return summarize(values), "line=" .. line
end

local function print_result(name, result, state)
  print(string.format(
    "BENCH %s count=%d median_us=%.3f p95_us=%.3f p99_us=%.3f max_us=%.3f total_ms=%.3f state=%s",
    name,
    result.count,
    result.median_us,
    result.p95_us,
    result.p99_us,
    result.max_us,
    result.total_ms,
    tostring(state)
  ))
end

vim.cmd("enew")
vim.bo.buftype = "nofile"
vim.bo.swapfile = false
vim.bo.filetype = "lua"

-- 起動イベントとlazy.nvimの予約処理が落ち着くまで待つ。
vim.wait(250, function()
  return false
end, 10)

if vim.env.NVIM_BENCH_IGNORE_EVENTS == "1" then
  vim.opt.eventignore = "all"
end

if vim.env.NVIM_BENCH_NO_VISUALS == "1" then
  vim.opt.cursorline = false
  vim.opt.relativenumber = false
  vim.opt.foldmethod = "manual"
  vim.opt.foldenable = false
end

if vim.env.NVIM_BENCH_CURSORLINE_NUMBER == "1" then
  vim.opt.cursorline = true
  vim.opt.cursorlineopt = "number"
end

if vim.env.NVIM_BENCH_NO_CURSORLINE == "1" then
  vim.opt.cursorline = false
end

if vim.env.NVIM_BENCH_NO_RELATIVE == "1" then
  vim.opt.relativenumber = false
end

if vim.env.NVIM_BENCH_MANUAL_FOLD == "1" then
  vim.opt.foldmethod = "manual"
  vim.opt.foldenable = false
end

local char_result, char_state = benchmark_char_input()
local line_result, line_state = benchmark_line_motion()
local word_result, word_state = benchmark_word_motion()
local search_result, search_state = benchmark_search_motion()

print_result("char_input", char_result, char_state)
print_result("line_j", line_result, line_state)
print_result("word_w", word_result, word_state)
print_result("search_n", search_result, search_state)
print(string.format("BENCH nvim=%s", vim.version().major .. "." .. vim.version().minor .. "." .. vim.version().patch))

vim.cmd("qa!")

各セルは中央値 / p95 / 2,000回の合計時間（µs / µs / ms）です。これは実行ごとの集計であり、2,000回分すべての生ログではありません。