Two quick tips to speed up Rails 3 on Heroku

Alex Peattie

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13 Aug, 2012

1 minute read

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There are lots of ways to speed up your Rails site, but here are two I see a lot of sites neglecting: gzipping and serving jQuery by CDN.

Enabling gzip on Heroku

Heroku’s Cedar Stack by default doesn’t gzip assets, which means everything is sent to the browser uncompressed. This goes against best practices, and can slow down your load times considerably. Luckily it’s a super easy fix. In your config.ru, just use Rack::Deflater before you run your application:

require ::File.expand_path('../config/environment',  __FILE__)
use Rack::Deflater
run MyApp::Application

Technically, we’re using DEFLATE rather than GZIP - there’s a good write-up of the subtle differences here.

Loading jQuery from a CDN

By default Rails 3 uses jQuery, and by default it serves jQuery through your app’s asset pipeline. This probably isn’t ideal - loading jQuery from a content delivery network (CDN) can speed things up significantly, Dave Ward has a great write-up of why that is. Again, it’s really simple to set up, thanks to the jquery-rails-cdn gem.

Full instructions are on Github, but basically you need to remove:

//= require jquery

from your application.js, and in your layout add:

= jquery_include_tag :google

I’d recommend sticking with Google’s CDN, but there are other options to choose from. Pingdom has a very thorough rundown of the pros/cons of the various CDNs out there.