Firefox memory usage

Firefox memory

The phenomenon that Firefox doesn’t free memory is called Firefox memory leak. How to reduce firefox memory usage?

About Firefox memory usage

Source: About the Firefox "memory leak" - kb.mozillazine.org/Memory_Leak

For those who remain concerned, here’s how the Firefox memory feature works. Firefox has a preference browser.sessionhistory.max_total_viewers which by default is set to –1. When set to this value, Firefox calculates the amount of memory in the system, according to this breakdown:

RAM and Number of Cached Pages
32MB	0
64MB	1
128MB	2
256MB	3
512MB	5
1GB	8
2GB	8
4GB	8

(reference: nsSHistory.cpp)

No more than 8 pages are ever cached in this fashion, by default. If you set this preference to another value, e.g. 25, 25 pages will be cached. You can set it to 0 to disable the feature, but your page load performance will suffer.

How to reduce firefox memory usage

Type about:config in the Firefox address bar and search for browser.sessionhistory.max_total_viewers in the seachbox at the top of the about:config page. Right click this entry and set the values to 0 in order to reduce firefox memory usage.

Reducing the amount of cached pages does not free memory though. At some point Firefox has devoured 999MB of memory, and despite the machine has still 3G of free memory, Firefox 11.0 becomes sluggish.

From an article Reducing Firefox’s memory usage by MozillaZine Knowledge Base we find two tips how to make Firefox to release memory - "Firefox add-on RAMBack" and "Restarting Firefox".

Firefox add-on RAMBack

MozillaZine Knowledge Base - RAMBack extension lets you clear internal Firefox caches without restarting Firefox. RAMBack 1.0 by Pavlov. RAMBack will cause Firefox to issue an internal notification to free up memory that is otherwise held for performance purposes.

RAMBack review - RAMBack extension adds a "Clear Cache" option under the "Tools" menu. Clicking on "Clear Cache" reclaims 10M of memory from 500M occupied, compared to restarting that releases 300 further megs. RAMBack seems to be not too effective tool.

Restarting Firefox

MozillaZine Knowledge Base - If you find that Firefox’s memory usage continues to grow after long periods of being open, you may want to consider periodically restarting Firefox to bring the memory usage back to reasonable levels. Close Firefox and select the Save and Quit option to reopen your tabs when Firefox restarts.

Good advice, nonetheless my Firefox 11.0 does not feature these options.

Still, restarting Firefox is the only way to reclaim the RAM Firefox wants.

Firefox restart script - If you are tired of having to restart Firefox the traditional way, then QuickRestart is an extension that you will not want to ever be without.

Restartless Restart 8 - This 15KB restartless add-on will add a "Restart" option under "File" menu and Ctrl+Alt+r hotkey.

2011 2012