Performance / Delay Issue with Wezterm

[laxman20]

I'm noticing a delay when switching panes when using Wezterm.

Moving from Neovim pane to Neovim pane is quick.
Moving from Neovim pane to Wezterm pane has a noticeable delay.
Wezterm to Wezterm and Wezterm to Neovim are quick

Wezterm version: 20230712-072601-f4abf8fd

Wezterm config:

local w = require('wezterm')
local config = {}

if w.config_builder then
	config = w.config_builder()
end

config.window_padding = {
	left = 0,
	right = 0,
	top = 0,
	bottom = 0,
}

-- config.color_scheme = 'OneDark (base16)'
config.color_scheme = 'nightfox'


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

local direction_keys = {
	Left = 'h',
	Down = 'j',
	Up = 'k',
	Right = 'l',
	-- reverse lookup
	h = 'Left',
	j = 'Down',
	k = 'Up',
	l = 'Right',
}

local function split_nav(resize_or_move, key)
	return {
		key = key,
		mods = resize_or_move == 'resize' and 'META' or 'CTRL',
		action = w.action_callback(function(win, pane)
			if is_vim(pane) then
				-- pass the keys through to vim/nvim
				win:perform_action({
						SendKey = { key = key, mods = resize_or_move == 'resize' and 'META' or 'CTRL' },
					}, pane)
			else
				if resize_or_move == 'resize' then
					win:perform_action({ AdjustPaneSize = { direction_keys[key], 3 } }, pane)
				else
					win:perform_action({ ActivatePaneDirection = direction_keys[key] }, pane)
				end
			end
		end),
	}
end

config.keys = {
	-- move between split panes
	split_nav('move', 'h'),
	split_nav('move', 'j'),
	split_nav('move', 'k'),
	split_nav('move', 'l'),
	-- resize panes
	split_nav('resize', 'h'),
	split_nav('resize', 'j'),
	split_nav('resize', 'k'),
	split_nav('resize', 'l'),
	-- splits
	{ key = '|', mods = 'SUPER', action = w.action.SplitHorizontal { domain = 'CurrentPaneDomain' }},
	{ key = '_', mods = 'SUPER', action = w.action.SplitVertical { domain = 'CurrentPaneDomain' }},
	{ key = '|', mods = 'SHIFT|SUPER', action = w.action.SplitHorizontal { domain = 'CurrentPaneDomain' }},
	{ key = '_', mods = 'SHIFT|SUPER', action = w.action.SplitVertical { domain = 'CurrentPaneDomain' }},
	-- remove Al+Enter binding
	{ key = 'Enter', mods = 'ALT', action = w.action.DisableDefaultAssignment },
}

return config

Neovim version: v0.9.2

Smart-Splits version: 1.2.4
Smart-Splits config (lazy config):

return {
	"mrjones2014/smart-splits.nvim",
	lazy = false,
	config = function()
		vim.keymap.set('n', '<C-h>', require('smart-splits').move_cursor_left)
		vim.keymap.set('n', '<C-j>', require('smart-splits').move_cursor_down)
		vim.keymap.set('n', '<C-k>', require('smart-splits').move_cursor_up)
		vim.keymap.set('n', '<C-l>', require('smart-splits').move_cursor_right)


		vim.keymap.set('n', '<A-h>', require('smart-splits').resize_left)
		vim.keymap.set('n', '<A-j>', require('smart-splits').resize_down)
		vim.keymap.set('n', '<A-k>', require('smart-splits').resize_up)
		vim.keymap.set('n', '<A-l>', require('smart-splits').resize_right)
	end
}

[mrjones2014]

Hmm... This all looks like exactly what I have. Are your dotfiles in a public repo? If so I can take your full Wezterm + Neovim configs for a spin locally and see if I can narrow it down from there.

[laxman20]

Ya you're right. Commenting out call s:write(s:format_var("true")) does get rid of the delay though.

Someone on Reddit let me know that it's happening for them on Windows, but not Linux.
I'm able to reproduce it on Windows and Mac.

[laxman20]

Setting verbose=9 and doing a pane switch makes a lot of wezterm cli calls

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"
Press ENTER or type command to continue

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"
Press ENTER or type command to continue

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"
Press ENTER or type command to continue

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"
Press ENTER or type command to continue

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'activate-pane-direction' 'Right'"
Press ENTER or type command to continue

Executing command: "'/opt/homebrew/bin/wezterm' 'cli' 'list' '--format' 'json'"
Press ENTER or type command to continue

I don't see the same on v1.2.1

[mrjones2014]

Are those logs for a single pane switch? If so it looks like it's doing wezterm cli list --format json way too many times for some reason 🤔

[laxman20]

Yup that’s for a single switch from left pane to right.

[mrjones2014]

Alright that's a good clue then. It does have to get current pane info a few times to double check that things are working properly, but that looks like too many to me. I'll open an issue to investigate further.