Already tried that with a clean install. made no difference.
I have McAfee active on the system and have Malwarebytes (free) installed to use as needed.
Try temporarily disabling McAfee, or making CCleaner an exception in McAfee, and see if that makes any difference.
We are aware that at least one other AV (ESET) has started preventing the clearing of browser profiles, it locks them as a ‘Browser Protection’ function.
See:
I have no idea if McAfee might now be doing the same, but it’s worth checking.
Malwarebytes in Free mode will not be interfering with a clean as it is scan on demand only.
A Tip though- After running a scan with Malwarebytes Free and closing Malwarebytes remember to right click on the icon in the System Tray, it may be in the overflow, and ‘Quit Malwarbytes’ to close it’s background service and stop it from giving you pop-ups.
Prevent these:
By doing this after running Malwarbytes free
PS. Windows Defender is all that you really need, although I do also have Malwarebyted free for extra manual scans. (and Malwarbytes Browser Guard extension in my Firefox).
You don’t need a 3rd party AV anymore so why pay for one?
Made no difference. McAfee has not caused any issues and has been there all along.
Hi Jeff_M:
I asked because antivirus programs are cited as a possible cause for some Firefox issues in the Mozilla support article Troubleshoot and diagnose Firefox problems. It’s also irrelevant if McAfee “has been there all along” if it was damaged during the upgrade from Win 10 to Win 11 and is causing unexpected glitches now. Have you tested your cache clearing while your McAfee real-time protection and McAfee firewall (if a bundled feature) are disabled?
It’s generally recommended that users disable any third party antivirus like McAfee, Norton, etc. before starting a Windows upgrade (or any recovery process like a system restore) to prevent potential conflicts that could interrupt the installation of Windows system files.
I’d suggest you check the status of your Win 11 system files using DISM and System File Checker (SFC). Open an elevated command prompt with Administrator rights and enter the command DISM /Online /Cleanup-Image /ScanHealth. If that scan does not detect any problems with your component store then run the command sfc /scannow to see if it can detect and repair any issues with your system files. If either of those scans detects a problem see the gHacks article Use DISM to Fix Issues SFC Can’t for more information about these scans. From my Inspiron 5584 / Win 10 Pro v22H2 machine:
We might have different definitions of “clean reinstall” of Firefox. As I noted in my 26-Aug-2025 post <above>, a reinstall of Firefox only affects the program files in the installation folder at C:\Program Files\Mozilla Firefox, and a Firefox browser refresh only removes your browser extensions and custom configuration settings but simply imports your bookmarks and other user data (including any corrupted data) from your old user profile back into your new user profile.
If you follow the instructions in my 31-Aug-2025 post <above> (i.e., you test with a brand new “empty” user profile created with Profile Manager) and clearing your cache at History | Clear Recent History | Everything still takes minutes after a few hours of browsing then I think we can safely assume your problem has nothing to do with CCleaner.
I don’t have a Win 11 v24H2 OS, so if your DISM and SFC scans do not detect any issues with your system files I suggest you post in Mozilla’s Firefox Community forum and ask if anyone there with a Win 11 v24H2 OS has noticed a significant delay while clearing their Firefox browsing history. I searched that forum and could only find one topic posted 12 years ago for Firefox for Mac at Why does it take so long to empty the Firefox cache in Firefox 22? that seems similar to the problem you describe so it’s possible there’s something unusual about your hardware components (e.g., you have a discrete graphics card that enables GPU hardware acceleration in your Firefox performance settings) or some Win 11 v24H2 custom setting that is causing your slow cache clearing.
Dell Inspiron 15 5584 * 64-bit Win 10 Pro v22H2 build 19045.6218 * Firefox v142.0.1 * Microsoft Defender v4.18.25070.5-1.1.25070.4 * Malwarebytes Premium v5.3.7.209-139.0.5357 * Macrium Reflect Free v8.0.7783 * CCleaner Free Portable v6.39.11548 * HDCleaner Portable 64-Bit v2.091
Ran both processes and both came back clean.
When I uninstalled Firefox , I removed everything. The reinstall had no bookmarks and no passwords. When tested at that point , there was no change. Cache clearing in Firefox was slow. Every other program worked fine. Only Firefox is affected. Imported the bookmarks and passwords after testing.
McAfee is working just fine. Have not had any issues with it after the Windows upgrade. After the upgrade to 11 , the only program with issues seems to be Firefox.
System: local clone maker with ASUS MB , 64-bit Windows 11 Pro (current build) , 8 gigs RAM , 1 Terabyte Seagate Barracuda
Very strange. Clearing the cache for Firefox in both Firefox and CCleaner has been really slow since upgrading to Windows 11. Just cleared the cache and instead of taking 10+ minutes , it only took 11 seconds. Nothing changed by me.
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Hi Jeff_M:
That’s good news. Thanks for letting us know.
Perhaps nukecad was correct that you just had to wait a few weeks to let your system “settle down” after the upgrade from Win 10 to Win 11.
If you haven’t already done so I’d advise that you permanently DISABLE your Windows Fast Startup power option as instructed in Option # 2 of Brink’s ElevenForum tutorial Turn On or Off Fast Startup in Windows 11 and then restart your system a few times to allow this change to take effect. The Fast Startup power option (also known as hybrid boot-up / hybrid shutdown) is enabled by default in Win 10 and Win 11 but it can sometimes interfere with the loading and initialization of drivers and services at boot-up and cause all sorts of unexpected glitches and problems with a wide range of programs, including software updates.
Dell Inspiron 15 5584 * 64-bit Win 10 Pro v22H2 build 19045.6218 * Firefox v142.0.1 * Microsoft Defender v4.18.25070.5-1.1.25070.4 * Malwarebytes Premium v5.3.8.212-140.0.5364 * Macrium Reflect Free v8.0.7783 * CCleaner Free Portable v6.39.11548 * HDCleaner Portable 64-Bit v2.091
Power setting is set to balanced on the system (desktop).
Hi Jeff_M:
I think you’re looking at your power plan setting, not your Fast Startup shutdown setting.
The Fast Startup power option is located in your shutdown settings under “Choose what the power buttons do”. As noted in Brink’s ElevenForum tutorial Turn On or Off Fast Startup in Windows 11, you might have to click the “Change settings that are currently unavailable” link if this setting is hidden.
As noted in that tutorial, you must be signed in as an Administrator to change that Fast Startup setting.
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Dell Inspiron 15 5584 * 64-bit Win 10 Pro v22H2 build 19045.6218 * Firefox v142.0.1 * Microsoft Defender v4.18.25070.5-1.1.25070.4 * Malwarebytes Premium v5.3.8.212-140.0.5364 * Macrium Reflect Free v8.0.7783 * CCleaner Free Portable v6.39.11548 * HDCleaner Portable 64-Bit v2.091
Since everything is now working fine after Windows 11 sorted things out , I will leave it as is. Never any issues when it was Windows 10.