Firefox 58.0 release overview

Mozilla plans to release Firefox 58.0 to the stable channel on January 23, 2018. It is the first major update for Firefox's stable channel of 2018.  Firefox 58.0 follows Firefox 57.0 which introduced major changes to the browser.

Our overview offers detailed information on new features, improvements and changes in Firefox 58.0.

Note: The user profiles created with Firefox 58 are not compatible with earlier versions of the Firefox web browser. If you want to retain the option to downgrade Firefox to a previous version, create a new profile for that version.

Executive Summary

• Firefox 58 user profiles are not compatible with older versions of Firefox.
• Firefox 58 features performance improvements, new WebExtensions API, and other improvements.

Firefox 58.0 download and update

Mozilla plans to release Firefox 58.0 to the release channel on January 23, 2018. Firefox users can run manual checks for updates on the day to install the new Firefox release automatically in the browser.

Select Menu > Help > About Firefox to run a manual check for Firefox updates.

Direct download links for Firefox installation files.

• Firefox Stable download
• Firefox Beta download
• Nightly download
• Firefox ESR download
• Firefox unbranded builds information

Firefox 58.0 Changes

Performance improvements

Mozilla engineers made several performance enhancing improvements to Firefox 58. Off-Main-Thread Painting moves rasterization to its own thread to improve the page rendering performance.

I reviewed Off-Main-Thread painting in Firefox in December when it was revealed in Firefox Nightly. Mozilla noted back then that the feature improved FPS benchmarks by up to 30% in Firefox 58 when compared to Firefox 57.

JavaScript Startup Bytecode Cache reduces the time between the "start of navigation" and when the "onload event for each website is fired".  Mozilla noted in December 2017 that Firefox with JavaScript Startup Bytecode Cache enabled loads pages "on average 43ms faster".

Also, WebAssembly Performance improvements.

Tab page, Homepage and Search Engine overrides

WebExtension capabilities improve with every new release. Mozilla wants to make sure that Firefox users are aware of some of the changes that extensions made in the browser.

That's why Firefox highlights when extensions changed the Tab page, Homepage or default Search engine in the Preferences.

If an extension changed one of the default or user set values, it is highlighted by Firefox. Even better, the name of the extension is listed so that you know right away which extension is responsible, and there is a "disable extension" button to disable it right away from the preferences page you are on.

WebExtensions API changes

Development of the WebExtensions-based add-on system is an ongoing process. A first initial set of APIs launched in Firefox 57 but work on improving those APIs and adding new APIs continued.

Firefox 58 features several API improvements. The Theme API supports new features to give theme creators more options and customization options.

Reader Mode, a feature of Firefox that converts articles on the Web into a format that improves readability, is now available via an API.

Firefox 58 features other improvements, including improvements to the webRequest API and a new option for extensions to change the default saerch engine. Mozilla added a prompt to prevent extensions from changing the search engine silently in the background.

Other Firefox 58.0 changes

• Firefox Screenshots improvements: screenshots can be copied and pasted directly to the Clipboard, and it works in Private Browsing mode as well.
• Credit Card Autofill support. You control the feature under Forms & Passwords on about:preferences#privacy. Note that this is rolled out gradually and may not be visible on your end yet.
• Nepali ne-NP locale added.
• Fixed a blank font issue if fonts for fonts installed in non-standard directories on Linux.
• Warning to inform users and site owners about Mozilla's gradual distrust plan for Symantec certificate authority.

 

• Firefox 58.0 Issues

Firefox 58.0 has two known unresolved issues that Mozilla hopes to address in future releases.

• Audio playback may be disabled on Firefox for Windows over Remote Desktop Connection sessions.  You can mitigate the issue by loading about:config?filter=security.sandbox.content.level and setting the value to 2.
• Users who run screen readers may run into performance issues. Mozilla suggest that users use Firefox ESR until the issue is fixed.

Developer Changes

• PerformanceNavigationTiming API implemented. It is controlled by the preference dom.enable_performance_navigation_timing (default true)
• Implemented PerformanceResourceTiming.workerStart to give sites options to measure the Service Worker start performance.

Firefox 58.0 for Android

One of the main new features of Firefox 58 for Android is support for runtime permission request prompts. Extensions that you install in Firefox on Android display permission requirements during installation.

If an installation requires additional permissions during runtime, a prompt is displayed to the user to accept or deny these permissions.

Other changes include:

• Support for Progressive Web Apps.
• Performance improvements thanks to JavaScript Startup Bytecode Cache.
• Option added to Sync only over non-metered connections.
• Bengali bn-BD and Nepali ne-NP added.
• Full screen bookmark management with folder support.
• Support for FLAC playback.
• Added ability to change the status bar color in themes.
• Removed Firefox Search widget from home screen.
• Safe Browsing protocol updated to version 4.

Security updates / fixes

Fixes are announced after the release of Firefox. We update the article once Mozilla publishes them.

Additional information / sources

• Firefox 58 release notes
• Firefox 58 Android release notes
• Add-on compatibility for Firefox 58
• Firefox 58 for Developers
• Site compatibility for Firefox 58
• Firefox Security Advisories