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Norton Security SymDaeman causing very high CPU usage
This concerns my use of Norton Security version 7.7 running on MacOS 10.12 (Sierra) on my MacBook. Time and again, but especially after restarting my MacBook Air or relaunching a browser, the fan will start running and the Activity Manager reveals that SymDaemon is causing extremely high CPU usage. I have seen similar posts in the past. The solution suggested by Norton is to remove and reinstall their app. That works, but only temporarily.
It is like using a sledgehammer to push in a thumbtack. I have yet to see anyone who has suggested exactly what the problem is, and it has led numerous users to abandon using Norton Security, AntiVirus, etc. One cannot remove the unix executable SymDaemon without disabling the Norton Security app.
I have found that, using the Application Manager, I can "force quit" the SymDaemon app. (This requires administration privileges. It cannot be done using the "Force Quit" app in the Apple menu.) This temporarily stops the app but Norton Security relaunches it a second later. However, this seems to be enough to break the link to whatever is causing the problem because the usage drops to a tiny fraction of its previous level. (The number of threads in Memory ramps back up to more than 60, but that does not seem to be a problem.)
I'm wondering whether a lesser solution might work, e.g., trashing "com.symantec.symdaemon.NFM.plist". (This resides in "/Library/Application Support/Symantec/Silo/NFM/Daemon/SymDaemon.bundle/Contents/MacOS/SymDaemon".) I believe that it will be regenerated by the app, perhaps after restarting or fixing Norton Security.
Any other suggestions?