Firefox Developer Browser offers peek at app performance

Paul Krill

With version 40 of the Firefox Developer Edition browser, Mozilla is adding performance tools to give developers a better understanding of what's happening in apps from a performance standpoint.

The new upgrades profile the performance of websites, apps, or games. "All performance tools can now be found grouped together under the Performance tab, for easier usage," said said Dave Camp, director of developer tools at Mozilla, and Jason Weathersby, Mozilla technical evangelist, in a blog post on Tuesday. "Performance is all about timing, so you can view browser events in the context of a timeline, which in turn can be extended to include a number of detailed views based on the metrics you choose to monitor."

The Performance tab contains a timeline featuring Waterfall, Call Tree, and Flamechart views. Waterfall view provides insight into what a browser is doing as it runs an app or site and features a graphical timeline of events. Call Tree examines how much time is spent on particular JavaScript functions, enabling developers to find bottlenecks in code, while Flame Chart shows the state of the JavaScript stack during each millisecond of the performance profile.

In other areas in the upgrade, Network Monitor gains the ability to collect data when the Network Tab is not active, and developers can see whether an asset is loaded from cache. With CSS docs integration, Developer Edition links with Mozilla Developer Network documentation for CSS properties, offering developers more information when debugging. Also, whitespace in the text node layout offers a better view of markup. The release features more than 90 bug fixes as well.