Fix Firefox Not Responding or Freezing

Firefox not responding is a specific kind of frustrating — the window is right there on screen, you can see your tabs, but clicking anything produces nothing. The title bar shows “(Not Responding)” and the only apparent option is to force-close it and lose whatever you had open. I have dealt with Firefox not responding more times than I would like, on different machines and for different reasons, and the thing I have learned is that the pattern of the freeze tells you almost everything you need to know about the cause. Firefox not responding on a specific website is completely different from Firefox not responding at random, which is completely different from Firefox not responding at startup. This guide covers every fix for Firefox not responding in 2026, starting with the pattern identification that saves you from trying fixes that do not apply to your situation. This fits into the wider topic we cover in our Google Chrome Errors.

Before working through fixes, observe when Firefox not responding occurs. Firefox freezing on one particular website points toward a heavy page, a media autoplaying, or a script conflict specific to that site. Firefox not responding when you open a new tab or switch tabs points toward an extension conflict. Firefox not responding randomly during normal browsing usually means memory pressure or a corrupt profile. Firefox not responding at startup — before any page loads — almost always means either an extension crash during loading or a corrupt profile. These distinctions matter because the fix for each is different.

Firefox Not Responding: Wait First, Then Diagnose

The first time Firefox not responding happened to me I immediately force-closed it. That was a mistake — Firefox had been loading a page with a particularly heavy JavaScript application and was simply caught in a processing spike. Given 30 seconds it would have recovered on its own. Before force-closing a Firefox not responding situation, wait at least 30–60 seconds and watch whether the title bar stops showing “(Not Responding)” and returns to normal. If Firefox recovers, the freeze was temporary and caused by page load rather than anything requiring a fix.

If Firefox not responding persists beyond a minute with no recovery, check Task Manager (Ctrl + Shift + Esc) and look at the Firefox entries. Multiple Firefox processes consuming high CPU simultaneously usually indicates a runaway script on a page — closing that tab is the solution. A single Firefox process at 100% CPU for an extended period is more likely a deeper issue requiring the fixes below. A Firefox process showing 0% CPU but still not responding indicates the process has hung rather than being overloaded — force-close is appropriate in this case.

Firefox Not Responding Fix 1: Clear Cache and Cookies

A bloated or corrupt cache is one of the most reliable causes of Firefox not responding on specific websites — Firefox keeps trying to load a broken cached version of the page instead of fetching fresh content from the server, gets stuck in the process, and freezes. I have cleared the Firefox cache to fix not responding issues more times than any other single fix, which tells you something about how often this is the actual cause.

1. Firefox menu (three lines, top right) → Settings
2. Privacy and Security in the left sidebar
3. Scroll to Cookies and Site Data → click Clear Data
4. Tick both Cookies and Site Data and Cached Web Content
5. Click Clear, confirm, then restart Firefox
6. Test whether Firefox not responding recurs on the same sites

If clearing the cache resolves Firefox not responding temporarily but it returns within a few days, the cache is growing too large before it auto-clears. Fix this permanently: Settings → Privacy and Security → Cached Web Content → uncheck Use recommended cache size and manually set a limit of 512 MB. Firefox not responding caused by cache bloat will not recur once the cache is capped at a manageable size.

Firefox Not Responding Fix 2: Test in Troubleshoot Mode to Isolate Extensions

Extensions are the second most common cause of Firefox not responding — a poorly coded extension, one that has not been updated for the current Firefox version, or two extensions conflicting with each other can cause Firefox to freeze consistently in ways that look like a Firefox problem rather than an add-on problem. Troubleshoot Mode disables all extensions temporarily and is the fastest way to confirm whether an extension is responsible.

1. Firefox menu → Help → Troubleshoot Mode
2. Click Restart in the confirmation dialogue
3. Firefox opens with all extensions disabled — use it normally and check whether Firefox not responding occurs
4. If Firefox is stable in Troubleshoot Mode, an extension is the cause
5. Exit Troubleshoot Mode, go to Firefox menu → Add-ons and Themes → Extensions
6. Disable extensions one at a time, restarting Firefox and testing after each, until the not responding issue stops
7. The last extension you disabled before stability returns is the culprit — remove it or check for an updated version

From what I have seen across various support forums and my own experience, the extensions most often linked to Firefox not responding are video downloaders, ad blockers with very large custom filter lists, and extensions that have not been updated in six months or more. If you have any extensions showing an outdated last-updated date, test those first — an extension built for Firefox 115 running on Firefox 134 is a strong candidate for causing not responding issues.

Firefox Not Responding Fix 3: Disable Hardware Acceleration

Hardware acceleration uses the GPU to render web content — which is faster on most systems but causes Firefox not responding on configurations where the GPU driver is outdated, incompatible, or under stress from other applications. I have had Firefox freeze specifically on video sites and pages with heavy animations that were perfectly stable on other browsers — disabling hardware acceleration fixed it immediately, and a GPU driver update resolved the underlying conflict.

1. Firefox menu → Settings → General
2. Scroll to Performance
3. Uncheck Use recommended performance settings
4. Uncheck Use hardware acceleration when available
5. Restart Firefox and test on the content that was causing not responding

If disabling hardware acceleration stops Firefox not responding, update the GPU driver through Device Manager → Display Adapters → right-click GPU → Update driver. After updating, re-enable hardware acceleration — the updated driver usually resolves the conflict and Firefox runs better with hardware acceleration than without it on most modern hardware.

Firefox Not Responding Fix 4: Reduce Memory Usage

Firefox not responding under high tab loads is almost always a memory management issue — the system runs out of available RAM, starts aggressively using the page file, and Firefox hangs waiting for memory operations to complete. Firefox provides tools to reduce its memory footprint without closing tabs:

• Enable tab unloading — Type about:config in the Firefox address bar, accept the risk warning, search for browser.tabs.unloadOnLowMemory, and set it to true. This automatically suspends inactive tabs when memory is low, directly addressing Firefox not responding caused by RAM exhaustion.
• Reduce content process limit — Settings → General → Performance → uncheck Use recommended performance settings → reduce Content process limit from 8 to 4. Fewer processes means less total RAM consumption, at the cost of slightly less parallel page loading.
• Force garbage collection — Type about:memory in the address bar and click Minimize memory usage. This triggers Firefox’s memory cleanup immediately and can free hundreds of MB without restarting.

Firefox Not Responding Fix 5: Refresh Firefox

The Firefox Refresh is the fix I reach for when Firefox not responding has become persistent — happening regularly despite cleared cache and disabled extensions. It restores Firefox to a clean state by removing accumulated configuration changes, corrupt preferences, and problematic session data, while keeping bookmarks, saved passwords, and browsing history intact.

1. Firefox menu → Help → More Troubleshooting Information
2. Click Refresh Firefox on the right side of the page
3. Confirm — Firefox closes, resets, and reopens
4. The post-refresh wizard offers to import settings from the old profile — import bookmarks and passwords but leave extensions — reinstall only the ones you actively need

What Refresh Firefox removes: all extensions and themes, customised toolbar layouts, modified about:config settings, and session data. What it keeps: bookmarks, passwords, form autofill, and history. If Firefox not responding was caused by a corrupt preference file or a problematic about:config change made months ago and forgotten, the refresh resolves it immediately.

Firefox Not Responding Fix 6: Create a New Profile or Reinstall

If Firefox not responding continues after a Refresh — which is rare but does happen — the Firefox profile has corruption that the Refresh cannot fully clear. Creating a new profile is the most thorough fix at the profile level:

1. Type about:profiles in the Firefox address bar
2. Click Create a New Profile and follow the wizard
3. Click Launch profile in new browser on the new profile
4. Test whether Firefox not responding occurs in the new profile
5. If stable, export bookmarks from the old profile (Library → Bookmarks → Manage Bookmarks → Import and Backup → Export Bookmarks to HTML) and import them into the new profile

For a clean reinstall when nothing else resolves Firefox not responding: uninstall Firefox through Settings → Apps, delete the remaining folder at C:Program FilesMozilla Firefox if it persists, and download the latest Firefox installer directly from the Mozilla website. Install fresh — Firefox reconnects to the existing profile automatically after installation.

Firefox Not Responding Pattern	Likely Cause	Fix to Try First
Freezes on specific websites	Corrupt cache or heavy page script	Clear cache; try in Troubleshoot Mode
Freezes on video sites or animations	Hardware acceleration conflict	Disable hardware acceleration; update GPU driver
Stable in Troubleshoot Mode	Extension conflict	Re-enable extensions one at a time
Freezes with many tabs open	Memory pressure	Enable tab unloading; reduce content process limit
Persistent, survives cache clear and extensions disabled	Corrupt profile	Firefox Refresh; new profile

Our guide on Firefox keeps crashing covers the related issue where Firefox closes entirely rather than freezing — the causes overlap significantly and several of the same fixes apply. Our guide on Firefox running slow covers the performance issues that often precede Firefox not responding — a browser that is running noticeably slowly is heading toward freezes if the underlying cause is not addressed. The Mozilla Support website has a crash and freeze reporting tool that analyses submitted Firefox diagnostic data and often identifies specific known issues affecting the version you are running.

Firefox Not Responding on Specific Websites: JavaScript and Media

When Firefox freezes specifically on certain websites while behaving normally elsewhere, the page’s content is almost always the cause rather than Firefox itself. Modern websites run significantly more JavaScript than they did five years ago — complex single-page applications, infinite scroll implementations, embedded video players, and real-time data dashboards can each legitimately push Firefox’s JavaScript engine to its limits. This isn’t Firefox misbehaving; it’s Firefox doing exactly what the website asked of it.

The practical approach: before calling a website “broken,” try it in a private window (Ctrl + Shift + P) with extensions disabled. If the site loads and stays responsive in private mode, the freeze is caused by an extension interacting with that site’s scripts. If the site is still slow in private mode, it’s the site itself — checking whether other browsers handle it better (Chrome or Edge) confirms this. Sites that freeze Firefox but not other browsers may be using APIs or features that Firefox’s implementation handles less efficiently in the current version, and the fix is waiting for a Firefox update.

Autoplay video is a specific freeze trigger that affects certain Firefox versions on pages with aggressive autoplay. When multiple videos attempt to autoplay simultaneously — particularly on news aggregator sites that embed multiple video players — Firefox’s media decoder can become overloaded. Firefox Settings → Privacy and Security → Autoplay → set to “Block Audio and Video” prevents autoplay from triggering this scenario.

WebGL and 3D Content

Firefox not responding specifically on pages with 3D graphics, maps, or WebGL content (three.js applications, interactive data visualisations, online games) is almost always a hardware acceleration issue with the specific WebGL implementation. Firefox uses WebGL for GPU-accelerated 3D rendering, and WebGL driver bugs cause freezes that look identical to JavaScript freezes but don’t respond to JavaScript-based fixes.

The confirmation: open about:support in Firefox and look at the “Graphics” section. “WebGL Renderer” shows which GPU is being used for WebGL. If it says “Google Inc. (ANGLE)” rather than your actual GPU name, Firefox is using an emulation layer rather than direct GPU access — which is slower and more prone to hanging on complex WebGL scenes. Updating the GPU driver usually resolves this by providing a proper WebGL implementation that Firefox can use directly. Alternatively, go to about:config and set webgl.disabled to true — this disables WebGL entirely and forces a software fallback, which prevents the GPU-related freeze at the cost of much slower 3D rendering.

Multiple Firefox Profiles and Profile Lock Files

Firefox not responding at startup — where the Firefox window briefly appears and then freezes before any page loads — is sometimes a profile lock file issue rather than a crash or freeze. Firefox creates a lock file in the profile directory to prevent multiple Firefox instances from using the same profile simultaneously. When Firefox crashes or is force-closed, this lock file isn’t removed, and the next Firefox launch detects the lock file, assumes another Firefox is running, and waits indefinitely for the lock to be released — which produces the appearance of “not responding” even though Firefox is functioning correctly, just waiting.

The fix: close any Firefox-related processes in Task Manager (Ctrl + Shift + Esc → look for “firefox.exe” and end all instances). Navigate to your Firefox profile folder (type %appdata%MozillaFirefoxProfiles in the Windows address bar), open the active profile folder (look for the one that doesn’t have “.default” at the end, or the most recently modified one), and delete the file named lock or parent.lock. Relaunch Firefox — with no lock file present, Firefox starts normally without waiting.

Antivirus and Firefox: A Specific Interaction

Unlike Chrome, Firefox uses its own certificate store rather than the Windows certificate store. This means antivirus SSL inspection products that work transparently with Chrome (because Chrome uses Windows certificates, and the antivirus installs its certificate into the Windows store) may not work the same way with Firefox — Firefox won’t recognise the antivirus’s certificate and may freeze or throw errors when HTTPS traffic is intercepted.

If Firefox not responding occurs specifically on HTTPS sites, or if Firefox hangs when loading pages that Chrome handles without issue, antivirus SSL interception is worth testing. The Firefox-specific fix (if you want to keep SSL scanning active) is adding the antivirus’s certificate to Firefox’s certificate store: Firefox Settings → Privacy and Security → scroll to Certificates → View Certificates → import the antivirus’s root certificate. Most antivirus vendors document how to do this for Firefox specifically. Alternatively, disabling HTTPS inspection in the antivirus (while keeping other real-time protection active) resolves the Firefox-specific certificate conflict without requiring certificate management. Our guide on Firefox Crashing on Startup covers an adjacent issue.

Our guide on network-related browser freezes covers the network layer failures that sometimes contribute to Firefox not responding during active page loads. For Firefox-specific performance improvements beyond fixing freezes, Mozilla maintains a comprehensive Firefox support knowledge base with performance tuning guides, memory management configuration, and user-submitted performance fixes organised by Firefox version and operating system. See also Microsoft Edge Keeps Crashing for a related case.