Photo: Jim Merithew/Wired

Last year Mozilla launched MemShrink, an aggressive campaign to trim Firefox’s memory footprint. Since then not only has the browser’s overall memory use dropped considerably, but the effort has been expanded to tackle add-ons, a common source of Firefox memory woes.

Now Mozilla programmer Nicholas Nethercote, head of the MemShrink effort, reports that a new patch to prevent Chrome-to-Content leaks in Firefox add-ons results in “a 4x reduction in memory consumption.”

The new code is currently in Firefox’s Nightly channel for those that would like to help test it against a wide variety of add-ons.

Firefox contributor Kyle Huey, who wrote the new patch, has more details on how it works and where the memory leaks in add-ons come from. Huey writes that “it’s a little early to be sure what effects this will have, but the amount of leaks we see on our test suite dropped by 80 percent. I expect that this change will also fix a majority of the add-on leaks we see, without any effort on the part of the add-on authors.”

Unfortunately the hope that add-on developers wouldn’t need to do anything to reduce their memory use hasn’t panned out. Mozilla has since discovered that “there is an unfortunate side-effect of all this amazing, memory saving goodness which directly affects add-ons that have been packed with older versions of the SDK.” Mozilla is now asking add-on developers using older versions of the Firefox add-on SDK to repack their add-ons before the MemShrink efforts arrive in a final version of Firefox.

Luckily for Firefox fans there’s plenty of time for affected add-ons to be updated since the latest MemShrink efforts won’t make it to the final release of Firefox for at least another 12 weeks. When they do Firefox users will hopefully see a considerable drop in Firefox’s memory use making for a faster, less RAM-hungry web browser.

Xmarks has had a change of heart.

The free bookmark syncing service had previously announced it was shutting down, but according to a new post on the company’s blog, there’s a chance Xmarks may soon be reborn as a paid service.

It was an outpouring of support from users that flipped the script. Xmarks has a small army of faithful fans, many of whom said they’d be willing to pay for the service after hearing Tuesday’s shutdown announcement. Based on the amount of interest, the company it decided it may be able to make a subscription model work as a sustainable business.

For now, Xmarks is asking users who would be willing to $10 a year for Xmarks to register their support on a new Pledgebank page. If you’d be willing to give Xmarks a few dollars to keep the service alive, you pledge your $10 over at Pledgebank (no credit card required).

There’s no guarantee that a premium version of Xmarks will happen. In fact, Xmarks CEO James Joaquin says company would need at least 100,000 pledges — five percent of their 2-million-strong user base — before Xmarks would consider a premium service. Even if all those pledges turned into real cash that would still only amount to half the $2 million Xmarks says it needs to break even each year. And as Joaquin points out, the conversion rate from free to premium users is typically more like 1 to 3 percent.

That’s a long way from Xmarks stated goals, but stranger things have certainly happened in the world of web startups.

Xmarks started as a Firefox extension for syncing bookmarks between your various Firefox installations, but soon expanded to work with Google Chrome, IE and Safari, keeping your bookmarks in perfect sync across all those browsers.

Unfortunately, despite an incredibly useful set of features and a 2-million-strong user base, Xmarks never found a way to make money. After failing to find a buyer and facing increasing costs with little or no way to recoup them, Xmarks announced that it would shut its doors in January, 2011. Over the following two days, Xmarks was inundated with users begging for a reprieve in the form of a paid version.

Now it seems the company is testing the waters to see how many of its enthusiastic users will actually put their money where their mouths are.

See Also:

• Popular Bookmark Syncing Tool XMarks to Shut Down
• Xmarks Syncs Open Tabs Across Browsers, iPhone
• Mozilla Gets Ready to Weave Syncing Into Firefox
• Opera Link Connects Your Bookmarks Across Browsers

Mozilla Labs has announced an update to its Jetpack extensions system that makes it easier for developers to write browser add-ons that more closely interact with a person’s computer desktop.

The new Jetpack SDK is version 0.7. It is quickly reaching the level of maturity required for it to become a standard feature in Firefox.

Jetpack is a new extensions framework for Mozilla’s browser designed to offer developers an easier, faster way to build browser add-ons using common web development tools like HTML, CSS and JavaScript. The Jetpack extension framework will not replace Firefox’s existing framework, which uses heavier code. But Mozilla expects to see many developers switch to the new framework once it’s complete.

While Jetpack was innovative when Mozilla first announced it, Google has since added an extension system to its Chrome browser that works on the same principles as Jetpack — using web-based tools like HTML and CSS. More recently Apple joined the fray by adding a similar extensions system to Safari 5.

Firefox’s lightweight extension framework has spent a long time in development. Jetpack graduated from Mozilla Labs (though the project is still hosted there) in March of 2010, but, while there was some speculation that Jetpack might end up in Firefox 4, that appears unlikely.

Still, the developer SDK is now at version 0.7 which brings three new APIs for developers to test. The panel API creates floating modal popups that appear on top of web content and browser chrome and persist until dismissed by users or programs. There’s also a clipboard API for interacting with the OSes clipboard and a notifications API which mimics the look of Growl to display messages to the user.

The Jetpack roadmap calls for another SDK release near the end of September and then Jetpack should hit 1.0 sometime in the fourth quarter of 2010. Once Jetpack 1.0 is stable look for it to begin working its way into Firefox.

In the mean time, if you’d like to test out Jetpack and see what the fuss is about just install the Jetpack add-on, which allows Jetpack to work within current version of Firefox. Yes, it’s a little weird, but for now Jetpack is an add-on that you use to install add-ons.

See Also:

• Latest Update Makes Jetpack Add-ons More Powerful
• Mozilla’s Jetpack Prepares to Take On Chrome Extensions
• Review: New Features Bring Safari 5 Up to Speed
• Chrome Extensions Are Cool, But They Can’t Match Firefox

If you ever doubted Firefox’s add-ons have played a major role in the browser’s success, Mozilla has some staggering numbers to prove you wrong.

The Firefox add-on website recently passed the two billion downloads mark.

That’s more add-ons downloaded than there are people on the web. Of course, that doesn’t mean everyone has add-ons installed — many of us have a dozen or more add-ons installed at any given time — but Mozilla has previously shown that some 150 million add-ons are in use every day.

Of course the word “add-on” is a little vague. Mozilla isn’t just counting web developer favorites like Firebug or YSlow, but also things as simple as Personas themes, which might explain why the numbers are so high. For instance, if you frequently change Personas, you’re downloading a new skin every time, and that drives the numbers up.

UPDATE: The original version of this post incorrectly stated that Mozilla was including individual downloads of Personas in its count. The two billion number is new downloads of extensions and themes since 2005. Personas are not included in the count.

Still, there’s no question that Firefox users love their add-ons, and Mozilla has the McDonalds-esque number to prove it.

If you’re looking to extend Firefox, or just curious about what other people are using, check out the new “Best of 2 Billion Firefox Add-ons” collection Mozilla has posted. There are number of web developer favorites, including the aforementioned Firebug and YSlow, as well as some other must-haves like NoScript, Xmarks and Greasemonkey.

See Also:

• Finding the Best Firefox Add-ons Gets Easier With New ‘Collections’
• Xmarks Syncs Open Tabs Across Browsers, iPhone
• The Best Chrome Add-ons for Web Developers

The popular Xmarks browser extension has added a new feature to sync open tabs across browsers and platforms. Xmarks, which started as a Firefox extension, is now also available for Google Chrome, IE and Safari, so this new feature has the capability to keep all of those browsers in perfect sync. It will now even allow you to sync your open tabs to the iPhone using the Xmarks web-based interface.

The new features bring Xmarks closer to Firefox’s own Weave syncing tool. Although Weave can handle some things Xmarks cannot — like form data and browser settings — Weave only syncs between Firefox installs.

If you frequently switch not just computers, but browsers (as many of us do), Xmarks offers a more universal syncing solution.

Once Xmarks is installed, you’ll need to create a web-based account if haven’t already. The new tab syncing feature is disabled by default, so make sure you head to the preferences panel (or page, it varies by browser) and turn it on. Once open tab syncing is enabled, just click the “open remote tabs” menu item and you’ll have access to any tab in any browser where Xmarks is installed.

Xmarks has long been a favorite for syncing bookmarks across browsers, but the new tab syncing features make it even more useful. Weave is nice, but for true cross-platform, cross-browser syncing, Xmarks is the way to go.

See Also:

• Mozilla Gets Ready to Weave Syncing Into Firefox
• New Firefox Designs Rethink Browser Bookmarks
• Opera Link Connects Your Bookmarks Across Browsers

Add-ons account for more than 70 percent of browser crashes in Internet Explorer 8, according to Microsoft.

The company released a whitepaper this week titled “Enhancing the performance of Windows Internet Explorer 8″ that outlines the various factors influencing performance and speed in its flagship browser. The whole report is available for download (as an MS Word .doc file, if you can believe it).

The other 30-odd percent of crashes in IE8 are caused by the browser, one of its subsystems (such as the download manager) or by malware.

When confronted with criticism about performance, especially crashes, browser makers are always quick to point their fingers at add-ons. And rightly so — add-ons are sometimes buggy and poorly tested. As a result, browser makers are now subjecting add-ons to a more rigorous testing process to vet their stability and safety before giving them the stamp of approval.

In a detailed analysis of Microsoft’s report at our sister site Ars Technica, Emil Protalinski argues that the third-party add-on culture around IE isn’t as robust as those surrounding Firefox and Chrome.

Protalinski chalks it up to IE being a poor development platform.

Microsoft’s two biggest competitors in the browser market, Firefox and Chrome, both put a big emphasis on add-ons. Microsoft claims that IE add-ons are very easy to develop and that it made sure the developer tools are not a separate download. That may be true, but IE still isn’t as good an extensibility platform as other browsers: it’s harder for plugins to intercept web traffic and so add-ons like NoScript are much harder to port.

During his keynote address at Microsoft’s recent MIX10 developer event in Las Vegas, IE general manager Dean Hachamovitch said that one of his team’s goals is to significantly improve the browser’s extensibility in the next version.

IE9 is due around the end of the year, but you can test drive it right now.

See Also:

• Internet Explorer 9 Shows Up Faster, But Still Lacking
• Microsoft to Double Down on HTML5 With Internet Explorer 9
• Microsoft Still Chasing the Competition With IE9