For any vim people, I thought you might find this useful. As people who have paired on my machine can attest, I have had super slow performance once I have a few panes open in tmux. Turns out the problem was poor performance with syntax highlighting. Setting ‘set re=1’ in your .vimrc reverts back to a previous regex engine which is much faster. It’s like night and day.

https://stackoverflow.com/questions/16902317/vim-slow-with-ruby-syntax-highlighting