Mozilla Firefox 139.0 release binaries have been pushed out to mirrors today ahead of the formal announcement tomorrow. With the Firefox 139 browser update comes a few new features worth mentioning.

Firefox 139 delivers faster upload performance on HTTP/3 connections to the point that it's "significantly improved." Especially for HTTP/3 connections involving QUIC 0-RTT resumed connections and high bandwidth and high delay connections, HTTP/3 uploads should be much faster on Firefox 139 than with prior Mozilla Firefox releases.

Firefox 139 also includes full-page translation support within Firefox extension pages, PNG images with transparency are now preserved when pasting into Firefox, support for the WebAuthn largeBlob extension, timer throttling for workers, and support for the "hidden=until-found" attribute for content to be found in the via find-in-page but not otherwise displayed by default.

[1]

Some of the new experimental web features of Firefox 139 that are available but disabled by default include prioritized task scheduling, View Transition API, and disabling non-standard beforescriptexecute / afterscriptexecute events.

Those wanting to grab the official Mozilla Firefox 139.0 release binaries right now can do so via [2]ftp.mozilla.org .



[1] https://www.phoronix.com/image-viewer.php?id=2025&image=firefox_139_lrg

[2] https://ftp.mozilla.org/pub/firefox/releases/139.0/