Start Firefox in Safe Mode {web link}
A small dialog should appear. Click
Start In Safe Mode (not Refresh).
Is the problem still there?
It could be the work of one of your add-ons,
or it could be Hardware Acceleration.
How to disable Hardware Acceleration {web link}
Type about:addons<enter> in the address bar to open
your Add-ons Manager.
Hot key; <Control> (Mac=<Command>) <Shift> A)
In the Add-ons Manager, on the left, select Extensions.
Disable a few add-ons, then Restart Firefox.
Some added toolbar and anti-virus add-ons are known to
cause Firefox issues. Disable All Of them.
If the problem continues, disable some more (restarting
FF). Continue until the problem is gone. After, you know
what group is causing the issue.
Re-enable the last group ONE AT A TIME (restarting FF)
until the problem returns.
Once you think you found the problem, disable that and
re-enable all the others, then restart again.
Let us know who the suspect is, detective.
[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode] {web link}
A small dialog should appear. Click
'''Start In Safe Mode''' (not Refresh).
Is the problem still there?
It could be the work of one of your add-ons,
or it could be '''Hardware Acceleration. '''
''[https://support.mozilla.org/en-US/kb/forum-response-disable-hardware-acceleration How to disable Hardware Acceleration]'' {web link}
Type '''about:addons'''<enter> in the address bar to open
your Add-ons Manager.
Hot key; '''<Control> ''(Mac=<Command>)'' <Shift> A) '''
In the Add-ons Manager, on the left, select '''Extensions. '''
Disable a few add-ons, then '''Restart Firefox. '''
Some added toolbar and anti-virus add-ons are known to
cause Firefox issues. '''Disable All Of them. '''
If the problem continues, disable some more (restarting
FF). Continue until the problem is gone. After, you know
what group is causing the issue.
Re-enable the last group '''ONE AT A TIME''' (restarting FF)
until the problem returns.
Once you think you found the problem, disable that and
re-enable all the others, then restart again.
Let us know who the suspect is, detective.