One of the side affects of developing a more robust, interactive and aesthetically pleasing website is the possibility of an adverse performance impact. When considering all of our potential audiences, it’s very important that we try to maximize the performance of EWU’s future site. One of the ways we are doing this is by following some performance rules, called “YSlow”, developed by the performance gurus at Yahoo!. I need to credit Ryan for bringing YSlow to my attention back when he first started here. Since being introduced to it I’ve been on the verge of obsessing over how we can make the new site faster.
So what is YSlow? YSlow is a set of 13 rules that affect the performace of a web page. Following the rules can lead to performance improvements of 25-50%. That’s a major improvement especially considering the rules are quite simple:
- 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
- Configure ETags
I’m not going to expand on each rule here but I’ve linked to the explanation for each rule on Yahoo’s site if you’re interested. With the possible exception of rule 2, using a CDN, we will be attempting to follow each of these basic rules when developing and deploying the new site.
Measuring page performance using YSlow has been made easy by means of a couple Firefox plugins. Yahoo has developed a Firefox plug-in for YSlow to use with the Firebug plugin (a must-have plug-in for web developers). The YSlow plug-in analyzes web page performance with respect to each of the 13 rules and then assigns a performace grade of A through F.
If these rules have the positive performance impact that we expect, my hope would be that we can apply the same rules to other web-based IT systems around campus.










