Slow assets compilation in development mode

Question

I have a large rails app with hundreds of coffee script files.

Sometimes when I make a tiny change in a coffeescript file or I switch the branch the whole assets are being precompiled and I have to wait a long time for load the page:

Started GET "/assets/application.js" for 127.0.0.1 at 2013-01-11 19:39:45 +0100
Compiled sprockets/commonjs.js  (0ms)  (pid 18142)
Compiled jquery.js  (2ms)  (pid 18142)
Compiled jquery_ujs.js  (0ms)  (pid 18142)
Compiled underscore.js  (0ms)  (pid 18142)
Compiled backbone.js  (0ms)  (pid 18142)
Compiled backbone_rails_sync.js  (0ms)  (pid 18142)
Compiled handlebars.runtime.js  (0ms)  (pid 18142)
Compiled moment.js  (0ms)  (pid 18142)
...and so on

I use the following assets configuration config/development.rb:

# Do not compress assets
config.assets.compress = false

# Expands the lines which load the assets
config.assets.debug = false

When I set config.assets.debug = false I have to wait quite long time for load hundreds of js files. The question is: how to find the golden mean? How to optimize assets configuration in the development mode for the large app?

Answer 1

Take a look at this middleware from the Discourse team. We've had great success with it in our rails 4 app -- took reload times down from a minute to 5 seconds in development.