By Matt Mickiewicz

How slow is your website?

By Matt Mickiewicz

Broadband connections mean nothing for users if your site is slow because it’s poorly coded or thought out.

YSlow, a new plug-in that integrates with Firebug , has just been released by Yahoo’s Expectional Performance Team to help you pinpoint and fix specific trouble spots.

YSlow evaluates 13 different performance factors and provides a letter grade to each. If for any reason you fail to score a straighth ‘A’, YSlow will provide additional detail to help you solve the problem.

Let’s see how did:

YSlow in Firebug

Overall 64/100 (or a “D”) largely because we don’t use a CDN (Content Delivery Network such as Akamai) nor Entity Tags.

Aside from rating performance factors, YSlow provides useful stats on the loading size of your website, for both brand-new visitors as well as return users who might have portions of your site still in their cache. Here’s how it looks:

Components Report in YSlow

Update: All the performance rules are described on Yahoo’s site.

  • The CDN thing to me seems a bit overboard and makes the tool less useful for most developers.

  • Thankfully, you can modify the scoring mechanism by editing the about:config file in Firefox.

  • I fail to see how a CDN is useful to small/medium projects?

    Certainly a topic for a blog post or article in the future.

  • I fail to see how a CDN is useful to small/medium projects?

    Justifying the usefulness is easy, justifying the co$t is another thing entirely.

  • Matt

    It’s a mild irony that this site reviews YSlow when Sitepoint’s website is one of the slowest websites to load that I read.

  • I like the way that the page for YSlow is actually graded an F.

  • Anonymous

    It’s “Exceptional Performance” not “Expectional Performance”, although, typo or not, expectional does seem like a more fitting name for it. It all comes down to user perception and expectation. A lot of users will put up with a slow site if they expect it will be. Matt being the case in point for his comment on Sitepoint’s loading times.

  • jim,my
  • jim,my


  • SEO Canada

    Seems you also need to know a fair bit of jargon to understand what you’re being told. What with eTags, CDNs, gzip components and http requests, it’s not for the beginner, I’d say (as a beginner).

  • Speaking of – can someone point me to how-to’s to enable gzip and expires headers? I was thinking in .htaccess, but that just seemed to break my site. Any links to info?

  • I couldn’t understand CDN and ETags. Can you explain the advantages of it?


  • McKenna

    A CDN is a content delivery network which caches media content (images, videos etc), mirrors the content to lots of different servers around the world and delivers them to the user from the most appropriate location (e.g. the server that’s closest to the user). Lots of companies use them. The most common one I have seen is Akami which serves’s images.

  • Anonymous

    this book explains all the performance rules:
    High Performance Web Sites

  • pippo

    it is incredible how many dumb, arrogant idiots surf the web just to leave their spammy and pointless comments.
    Sitepoint site is not slow it just features a lot of content unlike your undegraduate resumeè that u mantain on university free space.
    Dear jim if all you know about xss attacks is that pathetic 1995-style javascript alert, I suggest you buy some sitepoint’s fine book on the topic and get a bit more knowledge.

    I’m not related with Sitepoint, I just hate idiotic criticism.

  • Ryno

    Thanks for the heads up on an excellent little benchmarking tool and I think its a great way for beginners to become aware of potential clientside performance bottlenecks, even if they are not sure what the recommendations mean. But hey, that’s what Google is for!

  • MattCurry

    For fun I did a comparison of similar sites and how their YSlow scores stack up.

  • Not tried it yet, but it looks like it just rates you based on the technology you are using and not actual performance, as to be honest I’d give an F for performance, it’s unfortunately one of the slowest sites I visit. Firebug reports 4 seconds to load this page.

  • Karl – I agree with you 100%. That’s why we’re investing a lot of time and money into splitting off the MarketPlace & Contests onto their own dedicated server cluster. This will dramatically decrease the load on the articles/blogs/forums sections of our site, thus improving performance.

  • Good to hear, I do like to keep things “whizzy” when I’m browsing – Else I tend to switch to another browser window and forget to come back to the other one :)

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