[Bug]: Noticable delay on split pane navigation

[mister-choo]

What Operating System(s) are you seeing this problem on?

Linux X11

Which Wayland compositor or X11 Window manager(s) are you using?

DE: GNOME 46.0
WM: Mutter

WezTerm version

wezterm 20241119-101432-4050072d

Did you try the latest nightly build to see if the issue is better (or worse!) than your current version?

Yes, and I updated the version box above to show the version of the nightly that I tried

Describe the bug

Navigating from nvim pane to wezterm pane happens with about 2 sec delay

To Reproduce

nvim config

local root = vim.fn.fnamemodify('./.repro', ':p')

-- set stdpaths to use .repro
for _, name in ipairs({ 'config', 'data', 'state', 'cache' }) do
  vim.env[('XDG_%s_HOME'):format(name:upper())] = root .. '/' .. name
end

-- bootstrap lazy
local lazypath = root .. '/plugins/lazy.nvim'
if not vim.loop.fs_stat(lazypath) then
  vim.fn.system({
    'git',
    'clone',
    '--filter=blob:none',
    '--single-branch',
    'https://github.com/folke/lazy.nvim.git',
    lazypath,
  })
end
vim.opt.runtimepath:prepend(lazypath)

-- install plugins
local plugins = {
  -- do not remove the colorscheme! it makes testing nicer
  'folke/tokyonight.nvim',
  'mrjones2014/smart-splits.nvim',
  -- add any other pugins here
}

require('lazy').setup(plugins, {
  root = root .. '/plugins',
})

require('smart-splits').setup({
  -- add any options here
})

vim.keymap.set('n', '<C-Left>', require('smart-splits').move_cursor_left)
vim.keymap.set('n', '<C-Down>', require('smart-splits').move_cursor_down)
vim.keymap.set('n', '<C-Up>', require('smart-splits').move_cursor_up)
vim.keymap.set('n', '<C-Right>', require('smart-splits').move_cursor_right)

-- add anything else here
vim.opt.termguicolors = true
-- do not remove the colorscheme! it makes testing nicer
vim.cmd([[colorscheme tokyonight]])

Configuration

wezterm config:

local wezterm = require 'wezterm'
local config = {}
if wezterm.config_builder then
    config = wezterm.config_builder()
end

local function is_vim(pane)
    return pane:get_user_vars().IS_NVIM == 'true'
    -- return false
end

local direction_keys = {
    LeftArrow = 'Left',
    DownArrow = 'Down',
    UpArrow = 'Up',
    RightArrow = 'Right',
}

config.leader = { key = "a", mods = "CTRL" }

local function split_nav(key)
    return {
        key = key,
        mods = 'CTRL',
        action = wezterm.action_callback(function(win, pane)
            if is_vim(pane) then
                win:perform_action({ SendKey = { key = key, mods = 'CTRL' }, }, pane)
            else
                win:perform_action({ ActivatePaneDirection = direction_keys[key] }, pane)
            end
        end),
    }
end

config.keys = {
    {
        key = "v",
        mods = "LEADER",
        action = wezterm.action { SplitHorizontal = {
            domain = "CurrentPaneDomain" } }
    },
    split_nav('LeftArrow'),
    split_nav('RightArrow'),
    split_nav('DownArrow'),
    split_nav('UpArrow'),
}

return config

Expected Behavior

Navigation from wezterm pane to nvim pane to take the same amount of time as from nvim pane to wezterm

Logs

There is no output

Anything else?

No response

[mister-choo]

Made a good effort to find an existing issue, but looks like there isn't one. In smart-splits discussions on the topic it was suggested that some of the wezterm cli operations can be slow, which causes this.

[mister-choo]

Investigated this some more and looks like it's a problem with fish:
$ time wezterm cli activate-pane-direction Right

---

Executed in 122.03 millis fish external
usr time 3.97 millis 439.00 micros 3.53 millis
sys time 13.34 millis 79.00 micros 13.26 millis

In different shells there isn't a delay and time command add some strange time which isn't usr or sys time

[mister-choo]

After I fixed startup time on fish command started executing in more manageable 4 millis. Why could that be the case? It seems shell startup time affects the wezterm cli time, even if it was started as a subprocess