Users who want to enable it can do so under Tools > Options > Submit Performance Data, or by entering about:config into the Firefox address bar, filtering for the parameter toolkit.telemetry.enabled and setting that parameter to true with a double-click.

The Firefox browser will start to submit performance data – anonymously – to Mozilla. Mozilla notes that they do not use unique identifies like other browser developers do.

You might want to know exactly which data gets submitted to Mozilla once you enable Telemetry in the browser. You do not know that by default, as there is no option or setting to display the data. There is however an add-on available which displays the data that is collected by the Telemetry feature in the Firefox web browser.

About:Telemetry is a restartless add-on for Firefox that visualizes the data that is collected by the feature.

When you install the extension you can load about:telemetry in the browser to see the data that is collected by the feature.

Among the data is memory usage, startup profiling, http connection profiling and more. The collected data is probably not that interesting to regular users, other than verifying that the data that is submitted to Mozilla is performance related.

The extension checks if Telemetry is enabled and informs the user about it.

Should you enable Telemetry? That’s entirely up to you. Maybe you should if you are not satisfied with the browser’s performance or memory usage, as you can contribute to the efforts to improve the browser in those fields.

Telemetry delivers real-world performance information to Mozilla which the developers analyze to optimize the web browser further. Asa notes on his blog:

What we really need to measure in order to tackle our slowest code is real-world usage and that requires an entirely different way of thinking about performance and a new set of measurement technologies from what we’ve grown accustomed to over the last decade or so. It’s no longer good enough to optimize for the various performance tests and benchmarks available to us; we must optimize for the performance issues our users are experiencing in the real world. This is where browser telemetry comes in.

Have you enabled performance reports in the Firefox web browser?

The reason for the performance drop is simple. Web browsers like Firefox try to load all tabs at once, which increases the resource usage temporarily.

BarTab is a Firefox add-on that tries to resolve those issues by changing the default website loading behavior to on demand loading.

This basically means that tabs are only loaded when they become active for the first time. Only one tab is for instance loaded during system startup, all others remain inactive in the tab bar. This inactivity is indicated with transparency.

The same process applies if multiple websites are selected by the user to be loaded at once.

The browser extension can also unload tabs, to free up memory in the browser. A right-click on a tab displays two new context menu entries, to unload the selected tab or to unload all but the selected tab.

speed up firefox

The options contain several settings to change the default behavior. It is for instance possible to add sites to a whitelist so that they are always loaded when opened.

It is furthermore possible to unload tabs automatically after inactivity, to reduce the memory usage of the browser.

BarTab can speed up Firefox by loading tabs on demand, and the option to automatically unload loaded tabs keeps the overall system resource usage on a lower level.

The add-on is directly available from the Mozilla Add-on repository over at Mozilla.com.

Loading all tabs at the same time works fine if the tab count is low but it prolongs the loading time if it is high. Firefox users who use the Multi Links add-on or a similar add-on which allows them to open multiple links at once in new tabs might also experience a slow loading time if the selected links exceeds a few.

The Firefox add-on Load Tabs Progressively tries to fix the default tab loading behavior of the browser by loading tabs in batches.

It can for instance be configured to load a maximum of three tabs at the same time. Remaining tabs will then be loaded when one of the tabs has been fully loaded. Firefox will load all tabs progressively until they are all loaded.

load tabs progressively

Performance increases as tabs can be loaded faster. This increases both startup time of Firefox but also load times when lots of links are opened at once.

The Firefox extension can also mark unread tabs. This is unfortunately done in a rather irritating way so that most users might prefer to turn that additional feature off.

The options can furthermore be used to change the number of tabs that are loaded simultaneously. Firefox users with regular massive tab loading sessions might want to give Load Tabs Progressively a try to speed up their browser during those times. (via JKWebTalks)

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.