How to exit visual mode without a delay in Vim?

As Ingo explained. Just thought I would post the solution: https://github.com/Greduan/dotfiles/blob/47f92e4db29d4ead778d877a85082b271de130ed/vim/vimrc.vim#L332-L346

Works pretty well. It's a little bit confusing for me as well, so I can't really explain, but the code explains itself pretty well.

The point is it works, it simply makes <Esc> work immediately even when on Terminal. I believe if you do have mappings set to <Esc> it'll give you time to do those as well. However I'm not sure.

EDIT

Studied a bit and I can now explain it. Basically, if you're not using a GUI (like MacVim) then when you enter insert mode the ttimeoutlen will be set to 0. Meaning that as soon as you click <Esc> that'll work. However once you're in normal mode then it'll set the ttimeoutlen to the number you prefer, letting you do mappings with <Esc>.

Perfect solution I think, since if you have mappings in insert mode it'll be using control or something like that.

EDIT 2

Here's the code:

set timeout " Do time out on mappings and others
set timeoutlen=2000 " Wait {num} ms before timing out a mapping

" When you’re pressing Escape to leave insert mode in the terminal, it will by
" default take a second or another keystroke to leave insert mode completely
" and update the statusline. This fixes that. I got this from:
" https://powerline.readthedocs.org/en/latest/tipstricks.html#vim
if !has('gui_running')
    set ttimeoutlen=10
    augroup FastEscape
        autocmd!
        au InsertEnter * set timeoutlen=0
        au InsertLeave * set timeoutlen=1000
    augroup END
endif

With time I've removed the condition that the GUI isn't running and it still works as far as I can tell.

A quick workaround is using <C-c> instead, but you probably want to fix the timeout on <Esc>, which is caused by a mapping that starts with <Esc>, which makes Vim wait for 'timeoutlen' to check whether the mapping is complete.

This does not necessarily need to be a "real" mapping; many terminal workarounds (e.g. to make certain keys work) advise to set up such a mapping. (Unfortunately, this is a difficult and complex issue.)

You can find the mapping via:

:verbose map <Esc>

Executing following command helped me:

set timeoutlen=1000 ttimeoutlen=0

see: http://www.johnhawthorn.com/2012/09/vi-escape-delays/.