While building Monocle, I noticed that deploys to Heroku were taking absolutely ages; specifically the asset pre-compilation stage. I tried a variety of things, including removing a bunch of CoffeeScript files, but deploys were still taking in the order of several minutes.
After talking to Josh, it seems the solution is a simple one. Simply enable Memcache caching for sprockets during the pre-compilation stage. By doing this, I’ve reduced asset compilation from 100 seconds to between 4-9 seconds.
By default, each Heroku deploy is in a isolated environment. This means that Sprockets can’t take advantage of previous asset compilations, and has to compile everything from scratch. The solution is to have a shared cache between deploys.
If you’re using Heroku, the first...