Firefox Release Notes

Performance improvements, including:

• Rendering graphics for Windows users by using Off-Main-Thread Painting (OMTP)
• Loading pages faster by changing how Firefox caches and retrieves JavaScript

Improvements to Firefox Screenshots:

• Copy and paste screenshots directly to your clipboard
• Firefox Screenshots now works in Private Browsing mode

Added Nepali (ne-NP) locale

In case you missed it—57 Release privacy and performance feature:
Users can enable Tracking Protection at all times. Learn how to turn Tracking Protection on.

Fonts installed in non-standard directories will no longer appear blank for Linux users

Various security fixes

User profiles created in Firefox 58 (and in future releases) are not supported in previous versions of Firefox. Users who downgrade to a previous version should create a new profile for that version. Learn about alternatives to downgrading on our support site.

Added a warning to alert users and site owners of planned security changes to sites affected by the gradual distrust plan for the Symantec certificate authority

Implemented the PerformanceNavigationTiming API

Added PerformanceResourceTiming.workerStart so sites can measure service worker startup time

Users running Firefox for Windows over a Remote Desktop Connection (RDP) may find that audio playback is disabled due to increased security restrictions. Learn how to mitigate this issue until it is corrected in an upcoming release.

Users running certain screen readers may experience performance issues and are advised to use Firefox ESR until performance issues are resolved in an upcoming future release

When using certain non-default security policies on Windows (for example with Windows Defender Exploit Protection or Webroot security products), Firefox may fail to load pages (bug 1433065).