Mozilla's open source Firefox web browser has expanded its feature set significantly over the last several years. One byproduct of that feature set growth has been an expansion of the system memory that Firefox uses.
With Firefox 7, which is being officially released today, Mozilla is taking specific aim at reducing the amount of memory that Firefox uses. Mozilla has been actively working on reducing memory usage by way of the MemShrink effort. The goal of MemShrink is to find areas where Firefox memory management and usage could be improved.
The memory usage in Firefox 7 also benefits from a 20-line patch that Mozilla developers first talked about in June. The 20-line patch enables Firefox to start twice as fast on both Windows and Linux.
Firefox 7 has also fixed issues where memory usage would go up if the browser was left open for a long period of time, for instance overnight. Memory has also been improved by properly returning system memory when tabs are closed.
Overall, Mozilla developer Nicholas Nethercote blogged that Firefox 7 could improve memory usage by as much as 50 percent over previous versions of Firefox.
Performance is also improved by way of a new rendering backend that uses Direct2D technology.
"The bottom line is you should generally see a speed improvement using 2D Canvas in Firefox 7 when using Windows 7 or Vista with a sufficiently powerful graphics card," Mozilla developer Bas Shouten blogged.
Going a step further, Mozilla is baking in a new feedback system called Telemetry to help gather performance data. Telemetry is an opt-in system.
"Telemetry in Firefox is a new technology that allows our developers to build performance tests right into Firefox itself and to have those tests running while users are interacting with Firefox and the Web," Mozilla developer Asa Dotzler blogged. "These little tests, also called probes, should go completely unnoticed when you're using Firefox. But they make note of the time it takes to accomplish certain tasks like establishing a network connection or freeing system memory."
Firefox 7 is the fourth Firefox release from Mozilla this year and the third under their rapid release cycle. Under the new system, Firefox releases come out every six to eight weeks. While the new rapid release cycle enables Mozilla to push out new features faster, it has also raised concerns among enterprise users that can't or don’t want such a rapid pace.
As a potential solution, Mozilla has proposed an Extended Support Release (ESR) version of Firefox which will provide 42 weeks of support. The first ESR release is expected to be based on either Firefox 8 or 9.