Give this a try if still being allowed : go to the Firefox 3 Bar Menu --> Options --> Privacy & Security panel and under Permissions check (put a tick in the box) the setting to Prevent Accessibility Services from accessing your browser.

Please let us know if this solved your issue or if need further assistance.

Pkshadow said

Give this a try if still being allowed : go to the Firefox 3 Bar Menu --> Options --> Privacy & Security panel and under Permissions check (put a tick in the box) the setting to Prevent Accessibility Services from accessing your browser. Please let us know if this solved your issue or if need further assistance.

Hello, There seems to be no difference in performance.

maxiu said

Hello, I often use my multimonitor setup to watch Youtube video on one screen and browse the internet on another and while the video is playing in one Firefox window others are noticeably slower, this can be seen especially while scrolling through a page it feels like ~10 fps. My CPU usage is around 10-20% depends on the video quality. I tried disabling my addons but it didn't help. CPU is 2500k 4.4GHz and GPU is GTX 970. Thanks for any suggestions.

This isn't something of a FF issue but a Windows and Nvidia driver issue that your having. Did you ask Windows or Nvidia support forum about this?

SAFE MODE

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

In Firefox Safe mode these changes are effective:

• all extensions are disabled (about:addons)
• default theme is used (no persona)
• userChrome.css and userContent.css are ignored (chrome folder)
• default toolbar layout is used (file: localstore-safe.rdf)
• Javascript JIT compilers are disabled (prefs: javascript.options.*jit)
• hardware acceleration is disabled (Options > Advanced > General)
• plugins are not affected
• preferences are not affected

TEST if no problems is Extensions or Profile.

Please Refresh but do this 1st: Delete your Cookies and Cache and TEST.

• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

then

• https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings

TEST....... If no issues then Extensions which need to be added back in 1 at a time and tested ..... Or it is your Profile : Make a new one and test ...:

• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

If is your Profile :

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile
• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Note: Any customization will revert back to default, you will also need to reinstall Extensions.

Please let us know if this solved your issue or if need further assistance.

Pkshadow said

Hello, I followed your guide and refreshing Firefox helped, I got my extensions and setting back to where they were before and still can't replicate the issue so finally I don't know what the cause was, but it works perfect now.