Scott Ruthfield from WhitePages.com is announcing a new open-source projects called Jiffy, a tool for measuring the end-to-end performance of Web sites (PDF slides). Jiffy provides real data about performance that is more complete and more fine grained than what you might get from Keynote or Gomez. Jiffy has four goals:

• Real data at scale - track 100% of page views
• Measure anything - pre load data access, each add, brand, when the form is ready, and so on
• Real-time reporting
• No impact on page performance

Jiffy comprises a JavaScript library that instruments the pages, an Apache proxy, a tool for putting log data into a database (Oracle for now), and reporting roll-up code and UI.

The basic idea is "mark and measure." You can set a mark and then make any number of measurements of how much time has elapsed from the mark. You can do immediate or batch submits depending on the requirements or your site and how much bandwidth with want to consume.

Bill Scott of Netflix has written an extension to Firebug for Jiffy.