Firefox 140 ships with Unload Tab feature and new ESR base

[harlan4096]

Mozilla plans to release Firefox 140.0 to the Stable channel on June 24th, 2025. The new version of Firefox includes several usability improvements and new features, such as a new option to unload tabs to free up memory, improved vertical tab pinned tabs, faster full-page translations, and much more.

All other channels and versions of Firefox will also be updated around the same time. The Firefox ESR (Extended Support Release) versions are updated to 115.25.0, 128.12 ESR and 140.0 ESR respectively. Firefox 140 ESR is a new base for the extended support releases and it will replace 128.x soon. Firefox 115.25.0 ESR is still maintained for earlier operating system versions.

Last but not least, the development channels Firefox Beta, Firefox Developer Edition, and Firefox Nightly also move up a version to Firefox 141 and Firefox 142 respectively.

You can check out my review of Firefox 139 here.

Firefox 140: the major changes and new features

Tab Unload
 

The new feature is designed to free up memory while Firefox is running. Just right-click on any open tab in the Firefox web browser and select the new "unload tab" option from the context menu.

The tab remains visible but Firefox unloads it to free up memory. Unloaded tabs show up with gray icons to indicate that they are sleeping and not active.

The feature can be useful in some situations, for instance when the device is low on memory or when a website is "misbehaving" and consuming way too much memory or CPU.

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