Possible expensive syntax highlighting

[timss]

Current syntax rules can be slow when combined with Vim options such as cursorline that require a full redraw.

One of the reasons seems to be due to the use of lookahead and lookbehind regex (:h \@= etc). Unsure if this is avoidable with the current design or vimperator.vim's "fault".

Example Vim configuration:

set nocompatible
filetype plugin indent on
syntax on
set cursorline

Version:

$ vim --version
VIM - Vi IMproved 7.4 (2013 Aug 10, compiled Mar 31 2015 23:36:07)
Included patches: 1-488, 576
...

Example file: my personal .vimperatorrc

Resources:

• Ruby syntax highlighting w/ either cursorline or relativenumber causes lag from high CPU usage vim/vim#282
• Improve performance with syntax file (look-behind patterns: limit to length/bytes) vim-ruby/vim-ruby#243

[timss]

Note to self/interested contributors; this issue is still present with the example configuration.