In production mode, you have to run rake assets:precompile
to serve up anything in your app/assets
folder. In development, Rails constantly checks for updates to the files and serves them one-by-one.
This is great when you're developing, but is rather slow in production. So, to speed things up, Rails has you run a single, longer task that shrinks and combines a bunch of files in app/assets
, speeding up page loading times and reducing server load.