Firefox 139 beta improves upload performance of HTTP/3, translations and PNG support

Mozilla released Firefox 138 to the stable channel yesterday with several improvements that you can read about on Neowin. Alongside that launch, the company also released the first Firefox 139 update to the beta channel and it brings improved upload performance on HTTP/3 connections. To be clear, the beta channel gets updates three times per week so other features may get added before it’s released in several weeks.

Most users do not need to worry themselves about what HTTP/3 is, as it’s something the browser deals with behind the scenes. For users, it delivers faster page load times, improved performance on mobile networks, and enhanced security. Now, Firefox also uploads data over this protocol faster in this latest update.

The release notes state that upload performance on HTTP/3 has been significantly improved, particularly on resumed connections that use QUIC 0-RTT, as well as high bandwidth and high delay connections.

In addition to this, the release notes also state that full-page translations are now available in the Firefox extensions page and PNG images with transparency will keep their transparency when pasted into Firefox.

While these are certainly nice changes, Mozilla says on its release notes page that the features may or may not make it into the final release.

While delays are certainly possible, Mozilla is planning to release Firefox 139 on May 27, 2025 - less than a month from now. Alongside the stable release of Firefox 139, Mozilla will release Firefox 115.24 and Firefox 128.11 extended support releases. These two versions likely won’t see the HTTP/3 improvements and will instead just get security patches to keep users safe.

To stay abreast of future updates to the beta channel, you can bookmark the Firefox 139 beta release notes page.

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