Firefox 94/94.0.1 and 91.3.0esr

Mozilla[German]Mozilla's developers have released the version 94.0.0 and 91.3.0esr of the Firefox browser on November 2, 2021. And then the 94.0.1 was immediately added to correct a bug.


Firefox 94.0.0

According to the release notes, version 94.0.0 brings some new features as well as bug fixes and security fixes. Here is a rough overview of the new features:

  • Firefox macOS now uses Apple's power-saving mode for full-screen videos on sites like YouTube and Twitch. This significantly extends battery life during long video sessions. Mozilla says: Now your kids can find out what the fox is saying in an endless loop without you missing a beat….
  • With this release, power users can use about:unloads to free up system resources by manually unloading tabs without closing them.
  • On Windows, there will now be fewer interruptions as Firefox will no longer prompt you for updates. Instead, a background agent will download and install updates even when Firefox is closed.
  • And on Linux, WebGL performance has been improved and power consumption reduced for many users.
  • To better protect all Firefox users from side-channel attacks like Spectre, the developers introduced Site Isolation. It will be rolled out to Firefox 94 users in the coming weeks.
  • The developers are introducing the Firefox Multi-Account Containers extension with Mozilla VPN integration. This will allow users to use a different server location for each container.
  • Firefox no longer warns you by default when you exit the browser or close a window via a menu, button or three-button command. This should limit unwanted notifications, which is always good – but if you prefer a little notification, you still have full control over modal exit/close behavior. All alerts can be managed in Firefox settings. Don't worry about it! (More details)
  • And now Firefox supports the new snap layouts menus when running on Windows 11.

Furthermore, there are bug fixes in the new Firefox, which the developers describe with the following notes:

  • We've reduced overhead when using performance.mark() and performance.measure() APIs with a large number of performance entries.
  • We also changed the color suppression during charging to significantly improve warm charge performance in site isolation mode.
  • You will also notice a small reduction in Javascript memory consumption.
  • With this release, you will also notice faster enumeration of javascript properties.
  • We have also implemented better garbage collection scheduling which has improved some pageload benchmarks.
  • In this release, CPU usage is also reduced during socket polling for HTTPS connections.
  • You will also notice faster memory initialization.
  • We have also improved cold startup by reducing the I/O of the main thread.
  • In addition, closing devtools now reclaims more memory than ever before.
  • And we've improved page loading (especially in Site Isolation mode) by giving higher priority to loading and displaying images.

In addition, some vulnerabilities such as breakout from iframe sandbox or use-after-free vulnerabilities rated as high or moderate have been fixed in the new version.

Firefox 94.0.1

As early as November 4, 2021, Firefox 94.0.1 has been updated. According to the release notes, there was a bug that caused the browser to hang when displaying videos in full-screen mode under macOS 10.12. This is now supposed to be fixed.  

Firefox 91.3.0esr

An update of Firefox 91.3.0esr with one year of long-term support with the same fixed vulnerabilities was also provided respectively. 


The new Firefox and the ESR variants can be downloaded from this website for various platforms (the variant is to be selected via the displayed list boxes).

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