The memory usage of the browser was usually in the 300 to 400 Megabyte range on my computer, with a reasonable amount of tabs open and extensions installed. Reasonable in this regard means ten or less.

After updating Firefox to version 7, that memory usage went down to around 200 Megabytes, with the same amount of extensions installed and tabs open.

That’s a significant improvement for a browser that is perceived as a memory hog by many. Firefox users with a reasonable amount of RAM installed on their computer might not notice a difference in performance, but users with limited amount of computer memory surely will.

Another observation here is that the garbage collection and releasing of memory has been optimized as well, so that Firefox users will notice a drop in RAM use every now and then.

Firefox stable users, who are currently running Firefox 5, will have to wait another three months or so before they can update their version of Firefox to version 7. Beta users, currently running beta 5 will get access to the new version in about six week’s time.

Conceivable Tech report that Firefox 7 ships with additional improvements and features, among them an optimized synchronization feature, better font rendering, and a new Azure 2D graphics API that improves the browser’s 2D graphics performance significantly.

Firefox 7 scores better in the HTML5test, with a score of 312+9 out of 450. That’s less than 20 points from Google Chrome 14 which scores 329+13.

Firefox 6, the next beta and stable version of the browser, in contrast will be a rather uneventful update.

Computer users interested in the latest Aurora build of the browser can download it from the official Mozilla website. Existing Firefox Aurora users can update the browser with a click on Help > About Aurora.

If you are already running or testing the latest Firefox 7, what’s your impression so far?

One would normally assume that opening a tab increases memory usage, and that closing the same tab would drop memory utilization again to levels prior to opening that tab. That assumption up until now has not been true, which can be attributed largely to JavaScript fragmentation.

Firefox allocates 1 Megabyte chunks for the browser’s JavaScript heap. These chunks are returned once they are completely empty of data that is used by the browser. The only problem until now was that chunks contained objects and elements from various processes, sites and browser features.

Gregor Wagner analyzed the behavior and noticed that about 30% of the 1 Megabyte chunks could not be deleted because of small files that were still in use in the chunks.

Wagner implemented a patch that separated long and short lived objects by “placing system and user objects into separate chunks”. He defines long lived objects as browser elements that do not come from web pages. The core benefit of this approach is that chunks can be emptied a lot quicker which means that they can be returned to the operating system.

An improvement of about 30% was noticed on average on patched versions of the firefox web browser.

Closing all tabs after surfing:

• 108,003,328 B — js-gc-heap (without patch)
• 20,971,520 B — js-gc-heap (with patch)

Memory footprint of the whole browser:

• 310,890,496 B — resident (without patch)
• 219,856,896 B — resident (with patch)

That’s an impressive improvement which will likely make its way into the upcoming Firefox 7 browser.

Nicholas Nethercote posted a summary of Firefox memory improvements on his Mozilla based blog which includes information about George Wagner’s optmizations, but also information about other parts of the browser that get optimized.

Firefox users can look forward to the next but one version of the browser that ships with all those improvements. In related news, the first Firefox 8 Nightlies have been spotted on the Mozilla server.

Several third party applications tried to provide affected Firefox users with a solution to reduce the memory usage of the browser. Firefox Plumber is the last program to go down that route.

So how does it work? The developers are not explaining the inner workings of their program, only that they tweaked the memory handling. When you run Firefox Plumber you will notice a sharp drop in memory usage, usually down to a few thousand Kilobytes the most.

You will notice that the memory usage will climb up again and gets dropped again to the lowest possible amount from where it starts climbing up again. The memory usage won’t climb higher than a few thousand Kilobytes the most at any point in time though.

While it is not clear how the program does its magic, it is likely that it moves the memory to the disk cache. While that drops the memory usage, it also could slow down operations due to the slower speed of the hard drive in comparison to the computer’s RAM. It still can be beneficial if the computer has little RAM installed. The process does not seem to have an effect on the computer’s cpu usage though. At least on my modern PC I was not able to come to the conclusion that running the program did not affect the cpu usage.

When you close Firefox Plumber you will notice that memory usage increases gradually until it reaches the usual levels. The program comes with a configuration file in the program directory that lists the processes that it optimizes. Included by default are firefox.exe, plugin-container.exe and palemoon.exe. I did not try adding additional processes, Thunderbird comes to mind, to the ini but it could theoretically work.

Firefox users who want to reduce the browser’s memory usage can download Firefox Plumber from the developer website.

The developer has just recently released version 2.0 beta which adds native 64-bit Windows support. Users should keep in mind that it is still a beta version and not a final release.

Minimem when started displays the list of running processes on the operating system. It is then up to the user to select the processes that should be optimized by Minimem. The application displays only processes with a memory usage of at least 15000 Kilobytes. Users who want to see all processes can uncheck the option directly in the main interface.

Take a look at the Firefox process before and after the optimization. Please note that the memory will climb again but since the application optimizes the processes every 30 seconds it usually means that the resource usage is lower on average than without the optimization.

Minimem will not optimize the foreground process by default, and not at all if the available RAM is larger than 300 Megabytes. Both options can be deactivated or modified.

So what’s new in the beta besides the 64-bit support? Take a look at the changelog below.

Support for native 64 bits Windows OS; separate download file available
Memory colored indicator as tray icon, in addition to memory info in the tray icon tooltip
A last minute bug in this feature also got fixed and the build has been reloaded to our server on January 1 at midnight, EST time.
Localization of the application, with multiple languages available (feedback welcome to improve the translations!)
Engine optimization, so it uses even less CPU
More RAM thresholds available, for more granularity in their selection
Full rewrite of the architecture, hence the beta version because some bugs may still be there

Probably the biggest change is the engine optimization so that Minimem uses less cpu when running. Minimem 2.0 Beta is available from the developer webpage directly. Please take note that it is available as a 32-bit and 64-bit version. The program requires the Microsoft .NET Framework 2.0.

It does not really make sense to keep all tabs in the RAM all the time. Think about it. The monitor resolution limits the number of tabs that are shown to the user at the same time in default view. And practically, there can only be one active tab per browser window.

An extension to load tabs on demand is the next best thing, to a browser that uses an algorithm to only keep the active tab and the most likely to be opened tabs in memory.

BarTab does that. The extension has been this popular, that the developers have included part of its code in the upcoming Firefox 4 browser.

The extension offers more features and improvements, unlike Mozilla’s implementation, which only uses the functionality for the browser’s session restore.

The core functionality is similar though. BarTab basically offers functionality to keep only some of the tabs in memory. On session restore for instance, it will only load the first tab in the memory. All remaining tabs are restored but inactive. This speeds up the session restore in the browser noticeably.

This core functionality, and a lot more can be configured in the add-on’s preferences. But more about that later. A click on an unloaded tab in the browser loads it immediately. This means it will take longer to access tabs that are not loaded. The time depends largely on the speed of the Internet connection. New tabs are automatically loaded which is the default functionality in the browser. One interesting feature is the ability to unload tabs after a certain amount of inactivity. This is set to ten minutes by default, which means that active tabs that have not been visited in the last ten minutes will be unloaded automatically by the add-on.

bartab

Some users may have sites open that they want to access all the time. The preferences have an option to whitelist domains, so that they are not unloaded after inactivity, and always loaded if tabs are restored from a previous browsing session.

But how effective is the BarTab add-on? Can it be used to save RAM and cpu utilization while working with the Firefox browser?

• BarTab active, 1 tab loaded, 10 tabs unloaded, 110-130 Megabytes of RAM
• BarTab inactive, 11 tabs loaded 150-180 Megabytes of RAM

BarTab can save computer memory, and speed up session restores in the browser. The effectiveness of the add-on increases with the number of tabs open at the same time. The more it can unload, the better the effect on the browser’s memory usage. Firefox users with lots of open tabs, and users with computer’s that have a low amount of RAM will benefit from this add-on the most.

BarTab is available for Firefox 3 and Firefox 4 at the official Mozilla Add-on Repository.

Cache Status is a Firefox add-on that can clear the RAM and Disk Cache of Firefox automatically when it reaches a defined number. The add-on is not yet compatible with Firefox 3 right away but it works flawlessly if the install.rdf file is alterered that comes with the installation package.

To do that you need to download the Firefox extension from this link by right-clicking on the button and saving it to your hard disk. Now open the downloaded file with an unpacker like Winzip, Winrar or 7-Zip and extract the install.rdf file from the package.

Open install.rdf in a text editor and search for the line that begins with . Replace the complete line with the following line 3.0 and save the file. Now add the file to the installation package again and double-click it after that to start the installation.

The add-on will display the RAM usage of Firefox 3 in the status bar and it is possible to clear the RAM manually by right-clicking those information. If you want the RAM and Disk cache to be automatically cleaned you need to open the options of the add-on under Tools > Add-ons and click on the Options button of that add-on.

Just check the automatically clear .. options and define a percentage for each value when the automatically cleaning should kick in.

This does not seem to be the case however and RAMBack introduced a routine that reduces the memory usage of Firefox 3. Firefox 3 does keep some files in the cache for performance purposes and RAMBack will cause Firefox to issue an internal notification to free up memory.

A commenter on the add-on page said that this add-on “only clears the internet memory cache of sites not currently loaded in the browser” which makes a lot of sense to me. I had troubles finding a way to find out if the add-on is as useful as it sounds.

What I can say is that the memory usage seems to be pretty stable for the same amount of tabs and websites and that it does get reduced by a bit when closing websites. The author of the add-on seems to be heavily involved with the creation of Firefox 3 and it seems that this add-on is really doing what the description says.

Before I forget it. The website of the add-on does not state it explicitly but it seems that the add-on becomes active when the user presses the Clear Caches button in the Tools menu. Would have probably been better if it would automatically do that every x minutes or something instead.

Update:

Before someone says I’m not giving credit. I discovered this add-on in the Delicious Hotlist. Just realized that Lifehacker’s Adam Pash wrote about it as well.

After starting Firefox Ultimate Optimizer the RAM usage was reduced to 188 Kilobyte even with Firefox as the active window. The software does not have to be configured and sits in the system tray all the time.

I did scan it with Virus Total which did not find a single virus but I’m still puzzled on how this is achieved. I tried searching for more information but the developers homepage is down currently. It must be some kind of trick but I can’t find out how it’s done. If you know let me know please.

download at eSnips

The first and most important aspect is to consider removing themes and extensions which can really consume lots of memory. Before you start removing extensions you should do the following to see if it is possible to determine which extension or theme is responsible for the memory consumption.

• Starting Firefox in Safe-Mode
  • Safe-Mode disables all extensions and themes and loads Firefox with the default template. If this method uses continuously less memory a theme or extension is most likely responsible for the high memory consumption.
  • To run Firefox in safe-mode simply add the following parameter during startup “-safe-mode”.

• Problematic Extensions
  • Some extensions cause unwanted side effects. The Mozilla team is collecting information about those extensions which can be looked up here. You can try the suggested workarounds to fix the problem or uninstall the extension completely.

All the following tweaks can be achieved by typing in about:config in the Firefox address bar and entering (part of) the bolded parameter into the filter field.

• Browser.cache.memory.capacity
  • Controls the maximum amount of memory to use for caching decoded images and chrome (application user interface elements).
  • This determines if and how much system ram Firefox will use to cache itself. The element does not exist and has to be created. The default value is set to automatic which means that Firefox uses a certain amount of RAM by default. (values for Firefox 2.x)
    • 32 MB of RAM -> 2 MB
    • 64 MB of RAM -> 4 MB
    • 128 MB of RAM -> 6 MB
    • 256 MB of RAM -> 10 MB
    • 512 MB of RAM -> 14 MB
    • 1024 MB of RAM -> 18 MB
    • 2048 MB of RAM -> 24 MB
    • 4096+ MB of RAM > 32+MB
  • You can tell Firefox to use another value by creating the element in about:config and assigning a different value (in KB) to it. It is also possible to turn this feature of by assigning the value 0 to it. This can greatly decrease the performance of Firefox and is not advised at all.
  • To reduce memory consumption reduce the amount of RAM that is assigned to Firefox.

• Browser.sessionhistory.max_entries
  • Firefox 2.x saves the last 50 visited websites of a single session in memory which means that it could add up quickly if you visit lots of content filled websites.
  • Reduce the amount of websites that are stored this way to reduce the memory consumption. It does not make a huge difference for most surfing habits to reduce the figure to 5 or 10.

• Browser.sessionhistory.max_total_viewers
  • Automatically determine the maximum amount of pages to store in memory based on the total amount of RAM.
  • If you have 64 MB or Ram 1 page is stored in memory, 2 for 128 MB, 3 for 256 MB, 5 for 512 and 8 for everything higher than that figure.
  • If you never navigate using the Back and Forward buttons in Firefox you can set this value to 0 to disable the feature.
  • Otherwise reduce the amount of pages stored in memory to make this feature use less memory.

• Config.trim_on_minimize
  • This preference determines whether to allow Windows to reclaim memory from a minimized Mozilla application.
  • Set to True if you want to free up memory when minimizing Firefox.
  • The value does not exist by default, simply create it and set it to true for better memory management.