One of the articles linked below may help. Starting in troubleshooting mode (third link) would help and creating a new profile is a quick way of testing your existing profile. https://support.mozilla.org/en-US/kb/fix-common-audio-and-video-issues https://support.mozilla.org/en-US/kb/troubleshoot-and-diagnose-firefox-problems https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems (also deals with hardware acceleration) https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles

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