Relative numbering causes very slow highlighting

[alekratz]

Description of issue

Turning on relative numbering on files that are larger than a screen or so causes very slow highlighting. You can turn on relative numbering with :set relativenumber. It is important to note that I do not experience this with any other language with relative numbering enabled - it's just Perl 6.

Sample code:

Choose your favorite Perl6 file that has about 100 lines or more. For my tests I was using htmlify.p6 from the 'doc' library from Rakudo-star link

Link to vimrc

I don't have my vimrc online, and I am consistently able to get the extension to slow down using relativenumber. However, here are my plugins (I did disable them all except for Perl6, and was still encountering slowness with relativenumber enabled):

call plug#begin('~/.vim/plugged')
Plug 'wincent/terminus'
Plug 'godlygeek/tabular'
Plug 'fsharp/vim-fsharp'
Plug 'vim-perl/vim-perl6', { 'for': 'perl6' }
Plug 'rust-lang/rust.vim', { 'for': 'rust' }
Plug 'dag/vim-fish'
Plug 'vim-scripts/a.vim'
Plug 'vim-scripts/indentpython.vim'
Plug 'airblade/vim-gitgutter'
Plug 'ron-rs/ron.vim'
Plug 'hjson/vim-hjson'
Plug 'vimwiki/vimwiki'
Plug 'calviken/vim-gdscript3'
call plug#end()

Output of vim --version

VIM - Vi IMproved 8.1 (2018 May 18, compiled Dec  8 2018 11:23:48)
Included patches: 1-570
Compiled by Arch Linux
Huge version without GUI.  Features included (+) or not (-):
+acl               +extra_search      +mouse_netterm     +tag_old_static
+arabic            +farsi             +mouse_sgr         -tag_any_white
+autocmd           +file_in_path      -mouse_sysmouse    +tcl/dyn
+autochdir         +find_in_path      +mouse_urxvt       +termguicolors
-autoservername    +float             +mouse_xterm       +terminal
-balloon_eval      +folding           +multi_byte        +terminfo
+balloon_eval_term -footer            +multi_lang        +termresponse
-browse            +fork()            -mzscheme          +textobjects
++builtin_terms    +gettext           +netbeans_intg     +timers
+byte_offset       -hangul_input      +num64             +title
+channel           +iconv             +packages          -toolbar
+cindent           +insert_expand     +path_extra        +user_commands
-clientserver      +job               +perl/dyn          +vartabs
-clipboard         +jumplist          +persistent_undo   +vertsplit
+cmdline_compl     +keymap            +postscript        +virtualedit
+cmdline_hist      +lambda            +printer           +visual
+cmdline_info      +langmap           +profile           +visualextra
+comments          +libcall           +python/dyn        +viminfo
+conceal           +linebreak         +python3/dyn       +vreplace
+cryptv            +lispindent        +quickfix          +wildignore
+cscope            +listcmds          +reltime           +wildmenu
+cursorbind        +localmap          +rightleft         +windows
+cursorshape       +lua/dyn           +ruby/dyn          +writebackup
+dialog_con        +menu              +scrollbind        -X11
+diff              +mksession         +signs             -xfontset
+digraphs          +modify_fname      +smartindent       -xim
-dnd               +mouse             +startuptime       -xpm
-ebcdic            -mouseshape        +statusline        -xsmp
+emacs_tags        +mouse_dec         -sun_workshop      -xterm_clipboard
+eval              +mouse_gpm         +syntax            -xterm_save
+ex_extra          -mouse_jsbterm     +tag_binary
   system vimrc file: "/etc/vimrc"
     user vimrc file: "$HOME/.vimrc"
 2nd user vimrc file: "~/.vim/vimrc"
      user exrc file: "$HOME/.exrc"
       defaults file: "$VIMRUNTIME/defaults.vim"
  fall-back for $VIM: "/usr/share/vim"
Compilation: gcc -c -I. -Iproto -DHAVE_CONFIG_H   -D_FORTIFY_SOURCE=2  -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1
Linking: gcc   -L. -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fstack-protector -rdynamic -Wl,-export-dynamic -Wl,-E -Wl,-rpath,/usr/lib/perl5/5.28/core_perl/CORE  -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -L/usr/local/lib -Wl,--as-needed -o vim        -lm -ltinfo -lelf -lnsl    -lacl -lattr -lgpm -ldl   -Wl,-E -Wl,-rpath,/usr/lib/perl5/5.28/core_perl/CORE -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fstack-protector-strong -L/usr/local/lib  -L/usr/lib/perl5/5.28/core_perl/CORE -lperl -lpthread -ldl -lm -lcrypt -lutil -lc   -L/usr/lib -ltclstub8.6 -ldl -lz -lpthread -lm