Hi, What Extensions are you running and what Security Software ? 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 > Performance > Uncheck to view) *plugins are not affected *preferences are not affected TEST'''''''''is issue still there ? You may want to run a scan to see if something is slowing it down like malware : https://www.malwarebytes.com/ '''''To be Checked and turned off unless needed for accessibility : ''''' Please : 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. '''''Multi-Processor Support : ''''' Go to the 3 Bar Menu then Options --> General --> Performance and untick everything. change the recommended size lower then see how it runs. Note: 1 = No Multiprocessor = slow again. Try 2 if lots of ram try higher Restart Firefox after making these changes please. Note : Hardware Acceleration is for Video Card, Monitor to see if remain off or to turn back on.