Looking Towards Performance With YSlow

Recently during one of my trips down the internet rabbit hole I came across YSlow. This sweet little extension to Firebug blew me away. Firebug is already extremely excellent, I would say that it makes web development possible, but YSlow brings it all the way to your server and makes server optimization possible.

We all know that we should be worried about performance. That’s what everyone keeps telling us (but… will it scale?!?). And we’ve heard of all kinds of techniques that sound pretty cool which we should probably look into one day. And we always keep putting off performance optimization, after all it would be premature. Would my user even notice? But, thanks to YSlow I was able to easily identify at least a half a dozen things that I could do within minutes to improve my performance. All in all it took a couple of hours, mostly spent searching for how to enable the features in Rails an nginx that improve performance.

I won’t keep you waiting any longer, here’s how I turned my performance grade from a 48 to an 80:

1. Enable gzip compression

I’m using nginx, I know almost nothing about it (it’s Russian!), but because it is a well designed piece of software it was incredibly simple to accomplish a simple task. First: search google for nginx + gzip. Second: crack open your trusty ol’ nginx.conf. Third:

    gzip            on;
    gzip_comp_level 3;
    gzip_proxied    any;
    gzip_types      text/plain text/html text/css application/x-javascript text/xml application/xml application/xml+rss text/javascript;

Restart nginx and witness the savings.

2. Make Fewer HTTP Requests

I was serving something like 6 js files and 7 CSS files. Keeping them seperate sure makes it easy to navigate during development, but can really multiply your HTTP request count. Thanks to Rails this one is an easy fix too:

Before:

    = javascript_include_tag 'prototype', 'effects', 'dragdrop', 'application', :juggernaut
    = stylesheet_link_tag :all

After:
    = stylesheet_link_tag :all, :cache => true
    = javascript_include_tag 'prototype', 'effects', 'dragdrop', :juggernaut, :cache => 'base'
    = javascript_include_tag 'application'

Rails has caching enabled by default when running in production mode, but in order to take advantage of it you either need to read the docs or google that shit need to tell it what to cache. This gathers your multitude of files into one or two little happy files. They get even little-er when gzipped, though I am unsure what that does to their happiness. I also took this time to put my CSS above my JS. If possible the JS should be loaded nearer the bottom of the page (tell me more…). I’ll count that as a third and fourth thing I did to improve performance.

5. Add an Expires Header

If you’re like me you’re probably thinking: “What would Stevey do? Should I really become a wino? … and btw wtf is an expires header?” Step one. Step two:

        if ($request_uri ~* ".(ico|css|js|gif|jpe?g|png)?[0-9]+$") {
            expires max;
            break;
        }

Blast that into your nginx.conf. I’m not going to explain it. If you are still confused see step 1.

Well as you can see it was not quite half a dozen things, even with my creative counting. I hope this will help you get started on your road to glorious optimization using YSlow to tweak your Rails and nginx configurations. It’s tired in here… *honk-shu*

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