YSlow 0.9

December 7, 2007

I’ve mentioned YSlow – the firebug add-on that allows you to monitor what is slowing down your site. using YSlow I have found the most horrendous code in ‘free’ wordpress plugins that download all sorts of things your mother wouldn’t like, SEO tools that stuff cookies, unscrupulous developers using your site to boost their own stats. Its a tool that is essential if you’re doing any kind of forensic investigation into a site’s usability, speed and accessibility, for SEO or any other purpose. The good news is that they’ve just released version 0.9.

There are two big features in this release. By integrating more tightly with Firebug’s Net Panel, YSlow now finds non-DOM components such as Ajax requests and image beacons. And YSlow now crawls frames and iframes and analyzes those resources as well. There are several other new features and bug fixes described in the release notes including highlighting 404s, better detection of CSS expressions and JavaScript minification, and searching within the YSlow panel.

These features make YSlow stronger at identifying performance improvements for Web 2.0 applications. It’s great that YSlow does even better performance analysis of pages, but be forewarned that your previous YSlow scores will drop if these new-found components exhibit bad performance characteristics. As mentioned in Rule 14 – Make Ajax Cacheable, some of the performance improvements that are readily applied to static content (far future Expires header, gzip compression, minification) can also be applied to Ajax responses. Whether it’s Web 1.0 or Web 2.0, YSlow 0.9 helps you figure out what to fix to make your pages faster for your users.



August 13, 2007

I’ve been fiddling about with the new YSlow plugin. Basically its an addon for Firebug which analyzes web pages and tells you why they’re slow based on the rules for high performance web sites. Completely indispensable, and another good reason to switch to Firefox. YSlow gives you performance report card, HTTP/HTML summary and the list of components in the page, and its open source. Thank you.