Slow vim escape from insert mode

Question

When I press <Esc> from insert mode, it delayed about 1 sec, but if I just do <ctrl+c> instead it is fast.

I checked if there were mapping with escape with :verbose imap <Esc>, but I didn't find any.

Answer 1

It is mentioned in direct comments below the question itself. But just in case:

If you use tmux you may need to tweak escape-time. See explanation here and solution here.

.tmux.conf

set -g escape-time 10

# Or for tmux >= 2.6
set -sg escape-time 10

Do not forget to call tmux source-file ~/.tmux.conf after you change your config.
Also note that Neovim does not have set noesckeys, here.

Answer 2

There are two kinds of delay when you press <esc> in insert mode:

mapping delay

If you create some improper mapping that starts with <esc> :

inoremap <esc>x <esc>:echom "balabala"<cr>

When you press <esc>, vim will wait :h 'timeoutlen' milliseconds to see if next key is x.

You should avoid this kind of mapping in all modes, executes following commands to check if there exists this kind of mapping in all modes:

:verbose map <c-v><esc>
:verbose map! <c-v><esc>
               ^----------------press <c-v><esc> on your keyboard      

Mapping delay is controlled by :h 'timeout' and :h 'timeoutlen'.

keycode delay

Lots of terminal key code starts with <esc>, in my machine, <f5> is ^[[15~, ^[ is literal <esc>. When vim receives <esc> from your terminal, it waits :h 'ttimeoutlen' milliseconds to see if there are more characters in this key code, if there are none, then vim know it's truly a <esc>, otherwise it must be something else. This kind of delay is normal, you can change ttimeoutlen to reduce it.

Keycode delay is controlled by :h 'ttimeout' and :h 'ttimeoutlen' (not quite true, see :h 'ttimeout' for detail).

Common setting

set timeoutlen=1000
set ttimeoutlen=50

To be honest, i set ttimeoutlen to 5, 50 is still too much delay.

Answer 3

You could try set noesckeys. Here are its docs:

Function keys that start with an <Esc> are recognized in Insert
mode.  When this option is off, the cursor and function keys cannot be
used in Insert mode if they start with an <Esc>.  The advantage of
this is that the single <Esc> is recognized immediately, instead of
after one second.  Instead of resetting this option, you might want to
try changing the values for 'timeoutlen' and 'ttimeoutlen'.  Note that
when 'esckeys' is off, you can still map anything, but the cursor keys
won't work by default.

Answer 4

The latency you experience is most probably the consequence of some plugin. See this post on how to track possible culprits :-)

In resume:

:profile start profile.log
:profile func *
:profile file *
" Go into insert mode, do some editing (to force updates)
" Exit Insert mode with ESC
:profile pause
:noautocmd qall!

Answer 5

You might want to try changing ttimeoutlen.

As an example, Vim 8.0 introduces a $VIMRUNTIME/defaults.vim file which configures vim using more sane/modern settings. It contains these lines:

set ttimeout        " time out for key codes
set ttimeoutlen=100 " wait up to 100ms after Esc for special key

I personally have ttimeoutlen=0.

(Disclaimer: I don't fully understand everything that's going on with vim's timeout logic.)