web-masons/cornerstone-grunt — pull request #6 by hLittle (2014-11-19 21:33:01+00:00)
Title: Adding the option spawn: false

Speeds up the watch from about ~30 seconds to ~5 seconds for the compass and coffee tasks on vagrant.
https://github.com/gruntjs/grunt-contrib-watch#optionsspawn
May make the watch more unstable, but I think the performance gain makes up for it.