It's always a good idea to install MacVim with Lua support. Homebrew does not compile with Lua support by default. This gets you the benefit of a noticeably-faster Unite.vim.
Also, the option --override-system-vim will allow you to use vim in the command line apart from the GUI... also a great idea!
You have just read Speed up MacVim with Lua, written on April 14, 2015. This is Today I Learned, a collection of random tidbits I've learned through my day-to-day web development work. I'm Rico Sta. Cruz, @rstacruz on GitHub (and Twitter!).