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Zoompf's Web Performance Blog

Note: Archived Content

This is the archived version of the Zoompf blog. Since our acquisition by Rigor, all our new research and posts on web performance are being published on The Rigor Blog

What’s Your Website’s Performance Rank?

 Billy Hoffman on May 26, 2010. Category: Uncategorized

Lord Kelvin, the famous British scientist and mathematician, once said: “You cannot improve what you cannot measure.” Just as web developers track the quality of their code using unit testing, regression suites, and bug trackers to improve their work, performance metrics are needed as well.

So we created the Zoompf Performance Rank. This rank easily quantifies the performance status of your website. You can compare Performance Rank across different sites, or track how the performance of the same site varies over time.

photo of a score board

Zoompf’s Performance Rank for a website is calculated by scoring each response individually on a scale from 0 to 100. The score of all the responses are averaged together to yield the Zoompf Performance Rank . If a response has no performance problems it scores 100 points. For every performance problem a resource has points are deducted from that resource’s score. The number of points deducted is based on the severity of the performance issue. Critical defects, like not HTTP compression for a compressable response subtract 25 points.High severity issues like Unoptimized images are 15 points. The lowest score any resource can have is a 0. This only happens if the page has a large number of performance issues. No page will have a score less than zero. This means if your website only consists of 2 pages, one that is completely awful and the other is perfect, the lowest Performance Rank you can have is 50, regardless of how awful that awful page is.

Zoompf Performance Rank is a very flexible scoring system that more accurately reflects the performance of a site than other scoring systems. Let’s say you run a photography site that consists of 1 HTML page and 19 images. Let’s say you don’t have HTTP compression turned on so your HTML page receives a score of 75 while the images have no problems and each receive a score of 100. The Zoompf Performance Rank would be 98.75. Other tools might take off a large number of points because such a critical issue as HTTP compression is not turned on. However for this photography site, HTTP compression is not a big concern. The vast majority of the site, both in bandwidth and page count, would not benefit from HTTP compression. Now consider the same photography site. HTTP compression is now turned on for the HTML page (100 points), but all of the images are unoptimized (85 points each). The Zoompf Performance Rank is 85.75. Even though the performance problem is less severe, it affects the vast majority of the photography website and so has a lower Zoompf Performance Rank.

You can find our your Zoompf Performance Rank and test your website for over 300 performance issues right now using our free web performance scanning service. We also setup a Twitter account for the performance scanner (@zoompfauto) which tweets out the Performance Rank and a link to the full Zoompf performance report for every werbsite it scans. This is a great way to see how your site compares with others. As always feedback and questions are always welcome. Enjoy!

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