Note: you are advised to use vim-hexokinase instead. Or if you do not want to build a Go binary and want pure VimScript instead, you can try BourgeoisBear's fork which is expected to be faster and well-maintained.
A Vim plugin to colorize all text in the form #rgb, #rgba, #rrggbb, #rrgbbaa, rgb(...), rgba(...). See the comment at the beginning of the plugin for more options.
Screenshots:
The left screen shows colortest.txt in Vim in xfce4-terminal.
The right screen shows colortest.txt in gVim.
cd ~/.vim/bundle
git clone https://github.com/lilydjwg/colorizer
Use make install and make uninstall to quickly install/uninstall the
script, or simply copy plugin/colorizer.vim and autoload/colorizer.vim to
your .vim dir.
This version is based on https://github.com/lilydjwg/colorizer, also found as colorizer.vim on vim.org
This plugin is still inefficient for large files. I strongly sugguest you
enable it only when you need it, or set the g:colorizer_maxlines variable,
e.g. to 1000. There seems to be no way to get current displaying lines and do
work with them in Vim.