A while ago I wrote about about web performance and ad blockers. In that blog post I explained that I block ads because I can’t take the performance hit, that running an ad blocker or using Firefox’s tracking protection makes the web responsive again and a real pleasure to use. That blog post lead to discussions with a few people, including Mozilla intern Francesco Polizzi. Francesco and I discussed a study Tracking Protection in Firefox for Privacy and Performance (pdf) and how we could build on that. That study measured a 44% increase in page load performance and a 39% reduction in bandwidth usage across the Alexa top 200 news sites when tracking protection was enabled

So, ad networks, on average, are dramatically burdening page load times and drastically increasing data usage. This makes people sad and makes the Web less competitive with mobile. But publishers depend on ad networks for their livelihoods and surely some ad networks are better than others, right? Francesco and I wanted to quantify this and because Francesco is awesome, he created a browser extension for Firefox and Chrome, called SiteSonar, that identifies and benchmarks performance information about ad-related assets on the web as you browse.

(The extension uses Disconnect‘s list of ad domains to identify ad-related assets and then uses the WebRequest API to determine network response time for individual ad assets. That benchmark, along with information received like file size, status codes, and a timestamp are recorded locally. Finally, every few minutes the anonymous benchmarking stats are sent to a server where they’re parsed and logged into a database. The data powers a dashboard that displays aggregated information about ad network performance that the extension collected. To learn more, check it out on github.)

The early results from project SiteSonar are available at this dashboard. These are preliminary results from just a couple of us running the extension. We’d like to improve the results by broadening the base of people using this extension and submitting data. If you browse without an ad-blocker and would like to share some of your browsing history with us to improve the results of this experiment, you can find and install the Firefox extension at addons.mozilla.org and the Chrome extension at the Chrome web store.