Firefox constant 25% cpu usage in SANDBOXIE

Sandboxie 5.31.6 x64 on Windows 10 1909, FF 70.0.1 x64, similar issues I have reported previously in windows 7 and windows 10 1809.  Firefox safemode does not fix this... resetting firefox does not fix this, deleting sandbox and starting with a default profile does not fix this. It always happens after loading a number of tabs at once, say 4-12 tabs of that recreated it for me. Other times it just starts randomly. Setting Firefox Sandbox to 0 does not fix this. Running firefox outside of sandboxie fixes this.



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  • I did everything possible to try recreate this problem. Even loading a portable version of firefox in the same (or new) sandbox causes the same problem, even if I don't load any tabs it will often start after about 30 seconds with no warning, almost like on a timer.

    Without sandboxie I see 0.1 - 5% cpu browsing, hd movies 8-10%, only short fluctuations above this.  In sandboxie, once it is triggered, even if you have one empty tab it will consume 25% of the CPU's electricity constantly.

    I've ditched sandboxie for firefox until this is fixed

  • I get 0% CPU at idle with latest FF and Sandboxie with Windows 10 1809. The only other thing I would have pointed to is an addon that's conflicting with SB but I assume safemode disables the addons. You might consider disabling your AV and anything else that you might have running in the background.


    PS: Why does this forum break up words with hyphens? "ad-don"?

  • Just realized I didn't have any tabs open when I checked my CPU usage. So with 11 tabs open and a YT video playing at 720P I get between 5 to 6% CPU usage while sandboxed.

  • I get the same issue, and this has been happening for years. Firefox will behave at the beginning, but after longer use, something will trigger it to use more than 25% CPU all the time, no matter what it's doing. You could have a single blank tab and it would take 25% CPU. For me, I noticed that it was running GPU constantly, and with an integrated GPU, it means that the CPU is running constantly . Once it's triggered, no amount of closing and restarting firefox in sandboxie will cure it. The only remedy is to delete the sandbox and start over. This issue was raised in the old Sandboxie forum multiple times, but the developers never came up with a solution. 

  • This is the exact issue as happened to me. Resetting firefox does not fix this (that means deleting all addons/settings/and profiles.) No addons/safe mode does not stop this problem. Disabling firefox inbuilt Sandbox does not stop this problem. Disabling malware/virus protection did not fix the problem. Using a separate firefox installation does not fix the problem. Stop using sandboxie, fixes the problem. A few days before posting on here I had deleted my firefox sandbox entirely, not just temporary files. This stopped the issue for a short while, but it came back within a few minutes... however now no matter how many times I delete the sandbox and start a new one, it does not make a difference.

  • Same here. As Idzet says, the only temporary fix is to start with a new sandbox, but this only helps for several minutes before the problem returns.

  • I also have this issue for many months. It also happens when i have only 1 tab open. After ~60 seconds the CPU usage shows me 13% (because i have 4 cores with hyper threading enabled, so it is 1 virtual core used completely).

    The only thing i get rid of it is deleting the whole sandbox. Then cpu usage shows between 1% and 5%, which is normal. But after a while, the problem comes back.

    Outside of Sandboxie the problem is not there, and the cpu usage shows 1% to 5%, which is normal.

  • Still the same problem as described above. In the meantime my Firefox was updated to version 75.0. When the problem starts, only deleting the sandbox gets rid of it. Otherwise the CPU usage goes up to 13% after ~60 seconds of running Firefox (like described above) - when started outside of Sandboxie this does not happen and the CPU usage stays low. Probably it is now possible to find out the problem, because the source code is available to the public?