Improve speed of :vimgrep by using a global lock

autoload/sy.vim

@@ -18,6 +18,10 @@ sign define SignifyPlaceholder text=. texthl=SignifySignChange linehl=
 
 " Function: #start {{{1
 function! sy#start(path) abort
+  if g:signify_locked
+    return
+  endif
+
   if &diff
         \ || !filereadable(a:path)
         \ || (exists('g:signify_skip_filetype') && has_key(g:signify_skip_filetype, &ft))

plugin/signify.vim

@@ -5,7 +5,9 @@ scriptencoding utf-8
 if exists('g:loaded_signify') || !has('signs') || &cp
   finish
 endif
+
 let g:loaded_signify = 1
+let g:signify_locked = 0
 
 " Init: autocmds {{{1
 augroup signify
@@ -16,6 +18,9 @@ augroup signify
   autocmd BufRead,BufWritePost * call sy#start(b:sy_path)
   autocmd BufDelete            * call sy#stop(expand('<abuf>'))
 
+  autocmd QuickFixCmdPre  *vimgrep* let g:signify_locked = 1
+  autocmd QuickFixCmdPost *vimgrep* let g:signify_locked = 0
+
   if get(g:, 'signify_update_on_bufenter')
     autocmd BufEnter * nested
           \ if exists('b:sy') && b:sy.active && &modified |