Speeding up neovim when using rbenv

I’ve been using neovim for the last couple of years, and so far LOVE it. I did, however, initially, have an issue when opening ruby files. Opening ruby files would quite literally take neovim a few seconds to start up.

nvim --startuptime neobaseline.log somefile.rb
1426.382  1296.813  1296.813: sourcing /../ftplugin/ruby.vim
5149.924  000.013: --- NVIM STARTED ---

I did some additional profiling with vim and was getting similar results(albeit vim was a bit faster at loading ruby files). Seeing slowness with vim confirmed that it wasn’t just an issue specifically with neovim. After doing some additional profiling and researching online, I was able to get both neovim and vim to load significantly faster!

027  000.004: --- NVIM STARTED ---

137  000.002: --- VIM STARTED ---

Before I get too far, let’s go over my neovim setup(if you don’t care, skip to the solution section!).

Neovim/Vim setup

I hate having a massive .vimrc file, so I split out the configuration into multiple files. The config I use works with both neovim, and vim.

""""""""""Load Vim Config""""""""""""""
source ~/.vim/config/config.vim

""""""""""Load Custom Mappings"""""""""
source ~/.vim/config/mappings.vim

""""""""""Load Custom Scripts""""""""""
source ~/.vim/config/scripts.vim

""""""""""Plugin install"""""""""""""""
source ~/.vim/config/plugins.vim

""""""""""Plugin install"""""""""""""""
source ~/.vim/config/plugin-config.vim

The plugin manager I use is vim-plug. I won’t post my whole plugins.vim file due to the size.

" Neovim and vim8 support
if has('nvim')
  Plug 'Shougo/deoplete.nvim', { 'do': ':UpdateRemotePlugins' }
else
  Plug 'Shougo/deoplete.nvim'
  Plug 'roxma/nvim-yarp'
  Plug 'roxma/vim-hug-neovim-rpc'
endif

" Multiple syntax files
" Takes care of most things like vim-ruby, vim-javascript, vim-typescript etc
Plug 'sheerun/vim-polyglot', { 'for': ['ansible', 'cmake', 'crystal', 'clojure', 'dart', 'dockerfile', 'groovy', 'haproxy', 'javascript', 'jenkins' , 'jinja', 'json', 'llvm', 'lua', 'nginx', 'nim', 'pgsql', 'protobuf', 'ruby', 'eruby', 'haml', 'rust', 'swift', 'systemd', 'terraform', 'tomdoc', 'toml', 'typescript', 'yard', 'yaml', 'tmux', 'reason'] }

" Linting
Plug 'w0rp/ale'

Solution

After a bit of research and some trial and error, I found that using rbenv was a significant part of the problem. A ton of time was being spent by neovim and vim searching for the ruby binary and gems. Additionally, the provider/clipboard.vim was taking a long time to load for neovim.(This seemed only to be an issue for neovim).

Adding Plug 'tpope/vim-rbenv' to the top of my .vimrc, before most things were loaded, cut the startup time for vim by about half (interestingly enough, it didn’t do a whole lot for neovim)

  " Install plug manager early
  call plug#begin('~/.local/share/nvim/plugged')
  " Load rbenv plugin early on to speed up scripts that
  " look for ruby paths/gems etc
  Plug 'tpope/vim-rbenv'

Updating my plugins.vim to use more “On-demand loading”, helped a bit
```
  Plug 'tpope/vim-fireplace', { 'for': 'clojure' }
```

Specifying the ruby host prog in my config.vim(specifically for neovim)

  if has('nvim')
  " Tell neovim which ruby to use(ends up being rbenv)
  " The below should be handled by the tpope/vim-rbenv
  "
  " let g:ruby_path = system('echo $HOME/.rbenv/shims')
  let g:ruby_host_prog = '~/.rbenv/shims/neovim-ruby-host'
  let ruby_spellcheck_strings = 1
  endif

Specifying the clipboard settings

  if has('macunix')
  let g:clipboard = {'copy': {'+': 'pbcopy', '*': 'pbcopy'}, 'paste': {'+': 'pbpaste', '*': 'pbpaste'}, 'name': 'pbcopy', 'cache_enabled': 1}
  set clipboard+=unnamedplus
  endif

After making the config updates, both vim and neovim start almost instantaneously!

027  000.004: --- NVIM STARTED ---

137  000.002: --- VIM STARTED ---