Firefox Freezes After Running a While: Causes and Fixes

Quick answer: To fix Firefox freezing after running a while: (1) update Firefox (Menu > Help > About Firefox); (2) run Troubleshoot Mode (Menu > Help) which disables add-ons — if it stops freezing, remove the culprit extension; (3) clear cache and cookies (Ctrl+Shift+Del); (4) Refresh Firefox from about:support (keeps bookmarks/passwords, resets broken settings); (5) free RAM by closing tabs and heavy add-ons; (6) turn off hardware acceleration if the GPU driver is faulty; (7) create a new profile (about:profiles) if the old one is corrupted; (8) update the GPU driver and scan for malware.

Common causes

• Low RAM/CPU from many tabs and heavy add-ons.
• A faulty extension or a corrupted profile.
• Overgrown cache/cookies.
• Hardware acceleration issues or an old Firefox version.

How to fix it

1. Update Firefox to the latest version.
2. Troubleshoot Mode: Menu > Help > Troubleshoot Mode; if stable, disable extensions one by one in about:addons.
3. Clear data: Ctrl+Shift+Del > cache and cookies.
4. Refresh Firefox: about:support > Refresh Firefox to reset configuration while keeping your data.
5. Reduce load: close unused tabs; consider a tab-suspender; remove heavy add-ons.
6. Hardware acceleration: Settings > General > Performance > untick Use recommended performance settings and turn off hardware acceleration.
7. New profile: about:profiles > Create a New Profile.
8. System: update GPU drivers and run a malware scan.

Still freezing?

Check Task Manager to see if Firefox or another process maxes RAM/CPU, and make sure drive C has free space. If all browsers freeze, the problem is the PC (RAM, disk, overheating), not Firefox.