New Update Firefox 104: analyze a website's power usage and UI throttling

silversurfer

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" Firefox 104 Stable, Firefox 102.2 ESR and Firefox 91.13 ESR will be released later today. The releases fix security issues and bugs in Firefox; Firefox 104 Stable includes a handful of new features, including an option to analyze the power usage of specific websites. "
Executive Summary
  • Firefox 91.13 ESR is the last version of Firefox 91. Firefox 91 installations will be upgraded to Firefox 102 ESR on September 20, 2022, the next Firefox release day.
  • Firefox has a new power analyze tool in the Firefox profiler, which may be used to analyze a website's power usage.
  • Firefox will throttle its UI automatically when it is minimized or occluded to improve performance and battery usage.

Firefox 104.0 new features and improvements​


UI throttling

To improve the performance and battery of the device Firefox is run on, the browser will throttle its user interface whenever it is minimized or not occluded. The system works similarly to how background tabs are throttled by Firefox to limit battery drain and improve performance of the browser and the system as a whole.

Power usage analysis

Firefox users on Apple M1 and Microsoft Windows 11 devices may now use the Firefox profiler to analyze the power usage of a website.

firefox power usage website


Other changes and fixes

  • Firefox's Picture-in-Picture mode supports subtitles for Disney+ now.
  • The shortcut to paste unformatted text, Shift-CTRL-V on Windows and Shift-CMD-V on Mac, works in plain text contexts now.
  • Bypassing HTTPS-Only error pages and then going back takes Firefox users back to the originating site and not to the error page anymore.
  • The highlight color is preserved after "typing Enter in the mail composer of Yahoo Mail and Outlook".
 

silversurfer

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How to analyze the power usage of websites in Firefox​

Mozilla launched Firefox 104 recently, and with it a new Developer Tools option to analyze the power usage of websites. The feature is limited to Windows 11 and Apple M1 devices.

Power usage of devices has been in the focus for some time, but not on which activities require the most power on a device. The information may be useful, especially for mobile users who run their devices on battery sometimes or all the time. If battery is getting low, one could extend battery life by avoiding power hungry activities on the device.

To measure the power usage of websites in Firefox, Firefox 104 or later is required. This is the only prerequisite, other than running Firefox on a Windows 11 or Apple M1 device.

Note: the data is submitted to the Firefox website, where it is displayed.

power usage websites


Here are step-by-step instructions to check a website's power usage in Firefox:
  1. Open the website that you want to analyze.
  2. Select Menu > More Tools > Web Developer Tools, or use the keyboard shortcut Ctrl-Shift-I to open the interface.
  3. Optional: I suggest you move the interface to the bottom of the Firefox window by selecting Menu > Dock to Bottom.
  4. Switch to the Performance tab in the Developer Tools interface.
  5. Select the Power option under Settings.
  6. Activate the "Start recording" button.
  7. Use the website as you would normally.
  8. Activate the "Capture recording" button to end the recording.
  9. The Firefox Profiler website is loaded automatically.
  10. Locate the Power readings at the top (you may need to scroll down to find them).
 

silversurfer

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Firefox 104.0.1 fixes YouTube playback issues​

Firefox 104.0.1 is not yet available at the time of writing. Mozilla plans to announce the release later today, if you are reading this article on August 30, 2022.

Downloads will be provided on the official Firefox website but also as in-browser updates. Once released, Firefox users may select Menu > Help > About Firefox to run a manual check for updates. The window that opens displays the installed version and checks for updates by querying Mozilla servers. Any update found, and it should pick up Firefox 104.0.1 at that point, will be downloaded and installed automatically.

The Firefox 104.0.1 release notes have a single entry:
Addresses an issue with Youtube video playback that was affecting some users.

The changelog does not provide additional details on the issue that some Firefox users experienced. A bug report on Mozilla's bug tracking website provides the missing information.

According to the report, YouTube videos froze on some users since the update to Firefox 104. The bug poster linked to a thread on Reddit that was started five days ago.

The thread starter experienced random freezes on YouTube while using Firefox. One user suggested that the issue has been introduced by video performance improvements in Firefox 104 and that setting two preferences to FALSE would resolve the issue temporarily for affected users:
  1. Load about:config in the Firefox address bar.
  2. Confirm that you accept the risks.
  3. Search for media.wmf.zero-copy-nv12-texture.
  4. Set the preference to FALSE.
  5. Search for gfx.direct3d11.reuse-decoder-device.
  6. Set the preference to FALSE.
  7. Restart Firefox.
Mozilla implemented a fix in Firefox 104.0.1 that reverted the change to enable the zero copy feature. Once updated to Firefox 104.0.1, or one of the recent development build updates, Firefox users should not experience any freezes when playing videos on YouTube.
 

silversurfer

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" Mozilla plans to release Firefox 104.0.2 to the Stable channel today. The new version of Firefox fixes an out-of-memory crash, video and audio playback issues, and issues when using touch-devices or a stylus. "
Firefox 104.0.2 addresses four non-security issues in earlier versions of Firefox. The first fixes a crash issue that has been affecting 32-bit builds on Windows since the release of Firefox 102.

According to the bug report on Mozilla's bug tracking site and the changed code in Firefox, it appears that the issue was caused by reporting data specs, which could be "arbitrarily long". The issue is also fixed in an upcoming Firefox 102 ESR update.

Two of the issues fixed in Firefox 104.0.2 address video and playback issues in the browser. Both affected the playback of video and audio content in Firefox sometimes, according to Mozilla.

The issue occurred video and audio playback loaded via "a cross-origin frame src attribute" or with "Content-Security-Policy:sandbox". Both issues prevented playback of media and had similar causes. Firefox reused responses from the initial document in both cases for optimization. While that worked well for many use cases, it prevented the playback of media. Firefox users should not experience the described issues anymore after installation of the new version on Stable or ESR.

The fourth and final issue addresses an issue that affected touch-device and stylus users. The bug prevented touch and stylus users from dragging the scrollbar on pages.
 

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