Firefox 7 Beta 3: Improved Memory Management, Fixed Bugs and More

Mozilla this week launched Firefox 7 Beta 1, compared with the recent released Firefox 6, Firefox 7 is a bigger update, with much improved memory management and a host of similar features. There are all the usual improvements including enhancements to Firefox Sync, increased performance for HTML5 Canvas animation and better CSS3 support, but none of those really matter because there's one important improvement that isn't even visible to the user.

As we have seen on previous Firefox versions, there aren't important visible changes in this new release, but, nevertheless Firefox 7 is speedier and comes with bug fixes. Mozilla's next release of Firefox will be known for its significant reductions in memory utilisation, an issue that has dogged Firefox since its first release. Now Mozilla says it has implemented what it calls Memshrink in such a way that it expects somewhere on the order of a 20 to 30 per cent decrease in memory utilisation and sometimes as much as 50% less. In particular, Firefox 7′s memory usage will stay steady if you leave it running overnight, and it will free up more memory when you close many tabs.

Firefox 7 features proper remedy to the age-old memory leak problem. Instead of relying on the user to manually free up memory using the "about:memory" dialog, version 7 takes control of the process itself through increased garbage collection frequency and defragmentation of memory chunks, which will reduce Firefox's memory consumption by tens or even hundreds of megabytes over a lengthy period. In the meantime, how you can stop Firefox's increasing memory demands from spiralling out of control? The answer lies with a tiny add-on appropriately titled Memory Restart.

Memory Restart does two things: first, it displays Firefox's current memory consumption in the Add-ons Bar. This immediately reveals how Firefox's memory demands increase over time, regardless of how it's being used. When Firefox's memory consumption hits 500MB, the text will change to red to warn you that it's in danger of overrunning the rest of your system, telling you it's time to shut down and restart Firefox to free up most of the memory it's snaffled. Memory Restart's other trick is that you can configure it from its Options dialog to automatically restart Firefox when the 500MB threshold is reached, preserving all your open tabs and allowing you to continue browsing without too much hassle. Better still, the arbitrary 500MB figure can be altered to any amount you like, allowing you to tweak Memory Restart according to the amount of installed RAM in your computer.

There are two big changes in Firefox 7 that should reduce the memory footprint of Firefox for all users: increased GC frequency, and defragmentation of memory chunks used by various core Firefox processes. Increased GC frequency should massively improve the performance of Firefox over long, multi-day browsing sessions, and less fragmentation will result in memory footprints that are tens or hundreds of megabytes smaller than they currently are.

With the memory footprint squished, Mozilla’s attention will now hopefully turn to the desktop implementation of Electrolysis, the technology that separates content and core functionality into individual processes.
The reduced memory usage should also result in fewer crashes and aborts on Windows, where Firefox is built as a 32-bit application and so is typically restricted to only 2GB of virtual memory.
Mozilla’s MemShrink efforts are continuing. The endurance test results above show that development versions of Firefox 8 already have even better memory usage, and I expect we’ll continue to make further improvements as time goes on. We also have plans to improve our testing infrastructure which should help prevent future regressions in memory usage.

Version 7 also sees the Address Bar tweaked to resemble Chrome and Opera: that means the http:// prefix disappears completely (https:// still appears, however, for secure sites), while www. is also grayed out to emphasize  the domain name. While it seems to be only a cosmetic change, the purpose is to highlight the current browser location in a much more meaningful way and drop the protocol prefix, which has been confusing especially to users that are new or not familiar with the Internet. Firefox also greys out the "www" or subdomain of a URL, as well as the resource ID and deletes any trailing single slashes in a web address. To maintain a reasonable level of security while browsing, Firefox 7 still displays the https:// prefix, to inform the user when the browser is showing a "secure" webpage. Firefox will also include the prefix when users copy and paste URLs from the location bar. Mozilla is following both Chrome and Opera with the elimination of the prefix. Chrome dropped the prefix with the release of developer versions of Chrome 5 back in April of 2010.