Rails performance tip – using YSlow

Find out the performance of your rails site using yslow. YSlow requires the indispensable Firebug extension.

Download it from https://addons.mozilla.org/en-US/firefox/addon/5369/

YSlow checks your site in 13 scenarios as follows :-

  • Make Fewer HTTP Requests
  • Use a Content Delivery Network
  • Add an Expires Header
  • Gzip Components
  • Put CSS at the Top
  • Move Scripts to the Bottom
  • Avoid CSS Expressions
  • Make JavaScript and CSS External
  • Reduce DNS Lookups
  • Minify JavaScript
  • Avoid Redirects
  • Remove Duplicate Scripts and
  • Configure ETags

The easiest way to make fewer HTTP requests is to combine all JavaScript and CSS files into one. The asset packager plugin does exactly this, plus it will also compress the source files (in production mode) and correctly handles caching (without query string parameters).

Moving CSS to the top (within the head section) and moving JavaScript to the bottom of the page are both manual tasks that should be done in the layout templates (such as app/views/layouts/application.rhtml). Remember to use stylesheet_link_merged :base and javascript_include_merged :base rather than the default Rails helpers.

By using asset packager you can also verify that scripts are only included once – another performance hit otherwise!

Refer :- https://selvaonrails.wordpress.com/2010/09/10/assetpackager-in-rails/