Good afternoon. I do not know why my CPU usage during the period of inactiveness reaches 30%? can't say that my i7 6700-HQ is that bad? what should I do? have read all the CPU issues on forums. checked settings-adm. status "finished" for everything except explorer.
Hopefully this issue can be solved as several times I've returned to my idle computer to hear the fans humming away, and seemingly nothing else going on according to the MS Task Manager ! 
That sounds like a better solution Imacri. Does Imacri's solution address your CPU usage Book777?
Book777 presents a classic example of just how much time customers are spending trying to resolve this issue and it seems to be presenting for a few different reasons. Norton should step up and address this or at least acknowledge it.
JEJinMD's solution doesn't work for me. I spent many nights with auto-protect disabled to avoid the issue before I discovered my workaround.
book777:I found in "Task Schedule" a "\Norton Security\Norton Security Error Processor"...
Hi book777:
Those tasks are related SymErr.exe (Symantec Error Reporting) submissions - see noghere's thread Two New Start Tasks After Update to 22.12.1.14 Version as well as Symantec employee maverick786's comment in the thread symerr.exe.
I suspect a simpler (and safer) way to stop the idletime activity related to those tasks would be to simply set Detailed Data Error Collection to Never and Norton Community Watch to OFF in Settings | Administrative Settings as shown below. This will disable the Norton Community Watch submissions to Symantec during system idles (see Settings | Administrative Settings | Background Tasks | Configure for a list of Norton tasks that will run during system idles with default settings) and should also stop the logging of these submissions at Security | History under the headings Norton Error Reporting and Norton Community Watch. See the support article Norton Community Watch Settings.
The high CPU activity by nortonsecurity.exe being discussed in this thread appears to be related to a problem with Norton's real-time protection (Auto-Protect), not a "normal" background idletime task like Norton Community Watch.
---------------
32-bit Vista Home Premium SP2 * Firefox ESR v52.7.3 * NS Premium v22.14.0.54 * MB Free v3.4.5
I want to offer my solution of this problem:
I found in "Task Schedule" a "\Norton Security\Norton Security Error Processor" https://i.imgur.com/8jcxC08.png
That process runs after 5 min. of idle. Interesting. I try to delete this task, but it repair automatically after some time.
I write a small script to solve this https :// mega .nz/#F!BEZEjaAS!_ 5K7BwpJEe8RTUqBsJfPxg
You must unzip the archive to static folder (unchangeable) and run "Norton autodelete idle.exe" response must be "SUCCESS: The scheduled task "Norton delete idle processes" has successfully been created.". It program create schedule that in 4'th min idle remove all "\Norton Security\*" tasks.
If you afraid run "*.exe" from archive, then you can install a program "advanced bat to exe converter" and build programs from folder "\src"
[Edit: Removing external scripts to conform with the Participation Guidelines and Terms of Service]
I don't know if anyone else is watching this thread, but I have been dealing with this problem for a while, also - nortonsecurity.exe (SYSTEM user) grabbing 25% or 50% (that is 100% of 1 or 2 logical CPUs - I have 4 logical CPUs on this machine). After working with the usual solutions from the support folks (Norton Power Eraser, remove/reinstall, etc.) all I did to fix the problem (seemingly permanently) is right-click on the Norton icon in the system tray and select Auto-protect Disable. I disabled it for the default time period (15 minutes) and allowed the system to re-enable it after the timeout period. Since then, I have had no problems with the Norton program grabbing 25% or 50% of my system. I have re-booted, shut down and restarted, and I even did a full remove/reinstall earlier, and have had no issues after completely reinstalling the product.
I can confirm this: Visual Studio 2017 Community makes fight with norton's auto protect in idle.
I had never such problem before because I recently installed the visual studio, disabling that Net Framework NGEN tasks in Task Schedular seems like solved my problem.
Note that last NGEN Critical tasks were already disabled in my case, however first two on top (non critical) was "last run time" is today 4/14/2018 and completed with failure, (process terminated unexpectdly) with some random error codes, I guess thats Norton's doing.
But my problem is solved now, I don't know if these disabled tasks can restart themselves or not, so I think deleting them can fix this %30 CPU usage problem entirely? But I use Visual Studio to test my programs so I don't want lose my coding work in some way.
I will reply back here if the problem returns.
Hello there. Something went wrong again=(
Seems like I have to switch to Kaspersky or smth...
Hi Imacri,
The files in question are listed as trusted. Disabling sonar doesn't help. Adding the four files to the exclusions for auto-protect and sonar doesn't help.
The performance monitor shows Norton using moderate CPU but no alerts or notifications during the high CPU usage. Disabling auto-protect and allowing the tasks to run to completion does not generate any alerts or notifications. It did alert me to the Google Software Reporter Tool opening 394,331 handles. Looks like Google and Norton are both on the short list to be removed from my computers.
I'm done here. Hopefully Norton resolves the issue in a timely fashion.
Cheers and thanks again for all the suggestions and help.
Mick
mickhardy:..
The tasks launch the standard versions from "C:\Windows\Microsoft.NET\Framework\v4.0.30319\ngen.exe" and "C:\Windows\Microsoft.NET\Framework64\v4.0.30319\ngen.exe". They use less than 1% CPU if you disable auto-protect and complete on my machine in a few minutes. I'll try your other two suggestions on the virtual machine but I don't think they'll make a difference. It's not the files themselves causing false positives but what they do that clashes....
Edit: Those tasks do exist on a default installation of Windows 10 but they're disabled. I enabled them manually and it triggered this high CPU behaviour on a vanilla machine with just Norton. Default Windows 10, default Norton, enable the two lower NGEN tasks that run on idle and you'll get the persistent high CPU. No need to install Visual Studio.
Hi mickhardy:
No worries, I was just curious about the trust ratings of the NGEN files. If files like ngen.exe aren't fully trusted by Norton they might be triggering the real-time heuristic (behaviour-based) protection of Norton's SONAR (Symantec Online Network for Advanced Response - see the Behavior tab at https://www.symantec.com/theme/star) to "wake up" and monitor their behaviour, which would be a different mechanism than the "traditional" file-based (SHA-256 hash signature) detection of suspicious files during file scans. I don't know if there was an update to the SONAR engine around the time that your problem started but my assumption (which might be wrong) is that if these NGEN files are fully trusted / whitelisted then they should be ignored by SONAR.
It would be helpful if one of the Norton employees could follow up on this.
---------------
32-bit Vista Home Premium SP2 * Firefox ESR v52.7.3 * NS Premium v22.14.0.54 * MB v3.3.1
Waited for 20 minutes. 0% of usage. I guess that you successfully solved my issue!
Thank you so much! Good luck and have a great day!
Well that's a shame Vlad1ki3. It definitely fixed my two computers. I'm so used to the fans racing all night, it seems odd waking up to silence. Sorry I can't help any further.
mickhardy, didn't help for me. It took my PC around 15 minutes to slow down CPU usage by nortonsecurity.exe even after idle period was over. Still looking for a solution. Thank you all for helping me.
Thanks for responding TradesmanNorton. I wasn't entirely sure I'd helped anyone.
It will make some applications slower to start but most people won't notice the difference. It won't break anything but you should probably enable them again after Norton fixes the issue.
.Net applications need to be compiled into machine language before they will run. This happens automatically when you start the application. The Native Image Generator pre-compiles applications and stores them ready to go in a cache. It saves a little time.
It's like packing the car the night before a camping trip. You're quicker out the door and onto the road but it makes no difference once your driving.
Disabling maintenance entirely as suggested by Apostolos will affect many unrelated things including Windows security updates. It's like nuking a rabbit for digging holes in your garden.
Thanks for the feedback lmacri. The tasks launch the standard versions from "C:\Windows\Microsoft.NET\Framework\v4.0.30319\ngen.exe" and "C:\Windows\Microsoft.NET\Framework64\v4.0.30319\ngen.exe". They use less than 1% CPU if you disable auto-protect and complete on my machine in a few minutes. I'll try your other two suggestions on the virtual machine but I don't think they'll make a difference. It's not the files themselves causing false positives but what they do that clashes. I never tried Norton's performance monitoring. I was using Process Explorer and Task Manager. I'm unsure what extra details I could garner from Norton but I'll take a look.
Edit: Those tasks do exist on a default installation of Windows 10 but they're disabled. I enabled them manually and it triggered this high CPU behaviour on a vanilla machine with just Norton. Default Windows 10, default Norton, enable the two lower NGEN tasks that run on idle and you'll get the persistent high CPU. No need to install Visual Studio.
This worked for me. Thank you very much. Do you know if ends up having much impact on .net apps if they remain disabled?
lmacri:Apostolos:Under W 10, NGEN tasks run when Auto Maintanance is triggered, if there is no new Windows Cumulative update installed, those 4 tasks usually finish after a couple of minutes, however if there is a new Windows update all scheduled tasks are long to finish sometimes 20 mins sometimes 30 sometimes maybe one hour,depending also on pc's hw specs, and CPU and HDD suffer. Disabling Auto Maintenance solves that problem. If a user wants to re-enable it, personally I don't, it's very simple via regedit as I mentionned in my previous post.
Hi Apostolos:
I'm not doubting that your Win 10 registry tweak would be a viable alternative to mickhardy's workaround <here> to disable the Native Image Generator (NGEN) tasks in the Task Scheduler, but if nortonsecurity.exe (Norton AutoProtect) is responsible for the high CPU consumption during system idles because of out-of-date file trust ratings or some sort of conflict with a legitimate Windows software program like Visual Studio then I would prefer to see Symantec fix the issue from their end so that all affected users are helped.
---------------
32-bit Vista Home Premium SP2 * Firefox ESR v52.7.3 * NS Premium v22.14.0.54 * MB v3.3.1
NGEN tasks are not strictly related to Visual Studio, every W 10 system have those tasks in Task Scheduler and it's Microsoft who have programmed those tasks. I have not Visual Studio, however those tasks are on all my W 10 x64 systems and related to Auto Maintenance which is supposed, unfortunately, to run every 24 hours. As for Symantec, I do not think it's a high priority issue for them, I do not even know if it's possible to fix. If Norton "sees" a new Windows activity like a bunch of scheduled tasks it is supposed to monitor and check,and I do not think that it has to do with out-of-date file trust ratings or some sort of conflict, therefore my suggestion to disable Maintenance, many of those tasks are for telemetry purposes.
As for the tasks that are needed every user is able to do it manually, Windows allow it.
Hope this helps,
Apostolos:Under W 10, NGEN tasks run when Auto Maintanance is triggered, if there is no new Windows Cumulative update installed, those 4 tasks usually finish after a couple of minutes, however if there is a new Windows update all scheduled tasks are long to finish sometimes 20 mins sometimes 30 sometimes maybe one hour,depending also on pc's hw specs, and CPU and HDD suffer. Disabling Auto Maintenance solves that problem. If a user wants to re-enable it, personally I don't, it's very simple via regedit as I mentionned in my previous post.
Hi Apostolos:
I'm not doubting that your Win 10 registry tweak would be a viable alternative to mickhardy's workaround <here> to disable the Native Image Generator (NGEN) tasks in the Task Scheduler, but if nortonsecurity.exe (Norton AutoProtect) is responsible for the high CPU consumption during system idles because of out-of-date file trust ratings or some sort of conflict with a legitimate Windows software program like Visual Studio then I would prefer to see Symantec fix the issue from their end so that all affected users are helped.
---------------
32-bit Vista Home Premium SP2 * Firefox ESR v52.7.3 * NS Premium v22.14.0.54 * MB v3.3.1
@LMacri,
Under W 10, NGEN tasks run when Auto Maintanance is triggered, if there is no new Windows Cumulative update installed, those 4 tasks usually finish after a couple of minutes, however if there is a new Windows update all scheduled tasks are long to finish sometimes 20 mins sometimes 30 sometimes maybe one hour,depending also on pc's hw specs, and CPU and HDD suffer. Disabling Auto Maintenance solves that problem. If a user wants to re-enable it, personally I don't, it's very simple via regedit as I mentionned in my previous post.
mickhardy:Open Task Scheduler, navigate to Task Scheduler Library | Microsoft | Windows | .Net Framework and disable all tasks starting with .Net Framework NGEN....Visual studio configures these tasks and they're currently conflicting with Norton Security.
Nothing to do with Norton background tasks, it's Norton Auto-protect fighting with the Native Image Generator, which is supposed to improve the performance of .Net applications....
Hi mickhardy:
Thanks for the update, and good work isolating the cause of the high idle-time CPU by nortonsecurity.exe on your system. Kudos as well to Thel85 for the comment <here> about the .NET Optimizer.
I don't have Visual Studio or any tasks at Microsoft | Windows | .NET Framework in my own Task Scheduler so I can't follow up on my own machine. Do you know if these scheduled tasks launch the Native Image Generator tool (Ngen.exe) or some other NGEN executable mentioned in the Tom's Hardware thread Is it safe to disable ngentask.exe ?
If so, go to Security | Scans | Norton Insight | Go. Choose Untrusted Files (or possibly some other subset like All Loaded Modules) from the Show dropdown list and see if you can find Norton's current trust rating for your NGEN files. It's possible that a recent Windows Update updated some NGEN files that haven't been whitlisted (trusted) yet by Symantec, causing Norton's Auto-Protect to wake up and monitor these processes during system idles. If that's the case it might be possible to make a False Positive submission at https://submit.symantec.com/false_positive/ and have the file(s) tested and whitelisted so this high idletime CPU consumption by nortonsecurity.exe is corrected for all Visual Studio users.
Also, did you ever try to use the Norton Performance Graph as instructed in n333617's thread nortonsecurity.exe running at high cpu for long time to see if you could catch the name of the non-Norton process causing the high CPU? I'm just curious to know if these NGEN files were ever detected by the Performance Graph during system idles, since your image <here> showed that the NET Framework Optimization Service was only consuming about 0.2% of your CPU when your Norton Auto-Protect went into overdrive. That troubleshooting tip wouldn't help if that 0.2% CPU consumption is below the detection threshold for the Performance Graph.
---------------
32-bit Vista Home Premium SP2 * Firefox ESR v52.7.3 * NS Premium v22.14.0.54 * MB v3.3.1