Add Cache for compiled files

After a day of hacking, the project is far better than grunt.
But I found it will be very slow when I have a lot of coffeescript(almost 1000 - 2000 ms for each one). The page load speed is more than 20 seconds.
So I made some fix, add a simple cache, and then add a watcher, when the file changes, delete the cache. It works fine for me.