If you are like me and keep a close eye on tools that guage and monitor website performance, you no doubt have heard about Yahoo’s guide on Exceptional Performance:

“Yahoo!’s Exceptional Performance team evangelizes best practices for improving web performance. They conduct research, build tools, write articles and blogs, and speak at conferences. Their best practices center around the rules for high performance web sites.”

There is a section on “Rules for High Performance Web Sites” and at the bottom of the Exceptional Performance web page, the tool “YSlow” is introduced.  Being a tool junkie, I thought I would take the YSlow for a spin and see how a few different sites perform.

First up, Yahoo’s Exceptional Performance page: Performance Grade: C (71).  The two reasons why this page did poorly is because they failed to follow two rules:

I can see how it would be rather easy to add an “Expires” header; however, I take some issue with using a CDN (Content Delivery Network).  Yahoo describes CDN: “The user’s proximity to your web server has an impact on response times. Deploying your content across multiple, geographically dispersed servers will make your pages load faster from the user’s perspective. But where should you start?”

Yes, where should you start.  First of all, setting up a CDN is not exactly easy; and second of all, its not cheap…at all.  For 95% of the websites on the Internet today, it just isn’t practical to deply CDN. 

So, the question is, why doesn’t Yahoo use a CDN?  Who does use a CDN?

Next up, is Amazon.com.  Do they use a CDN?  Amazon is well-known for its infrastructure and near-perfect uptime.  Amazon’s home page: Performance Grade: F (51).  Problem areas where Amazon.com received an F include:

Frankly, I’m a little shocked that Amazon did so poorly; but, on second thought, I’m beginning to wonder if YSlow is being a bit too hard on websites, or perhaps I’m being a bit too hard on YSlow.

Next up, Slashdot.org, the bastion of all things good with the web comes in with a sad score: Performance Grade: F (49). 

Are there any sites that perform admirably?

Yes.  Google.com: Performance Grade: A (97).  Granted, the Google home page is so stripped bare that if it’s performance were anything below an A, I’d be hard pressed to consider YSlow to be less than a reliable tool.  Interestingly, even Google got a C grade on its use of CDN.

In conclusion, the YSlow tool can be useful to identify problem areas with a website and with perticular pages; however, its grading system could use some tweaking to be a bit more realistic with real-world websites.