What is 'LocalserviceNoNetworkFirewall' and How to Fix its High CPU ... 05.05.2022 · Many things can trigger a high CPU usage by the LocalserviceNoNetworkFirewall but we identified the following chiefly responsible for the issue: ... If the 3rd party security product like Avast Premium has become corrupt, ... Uninstall Avast Antivirus; Then follow the prompts to completely uninstall the product and reboot your PC.