After 8.5.5 update the system extension runs CPU 100%. --- did not happen before 7.5.5
Specifically the extension name is
Running Mac OS Catalina 10.15.3 with Norton 8.5.5 build 293 on MacBook Pro 15 inch, 2018 2.9 GHz 6-core i9
I can tell it's the Norton system extension because I see it using the Mac Activity Monitor.
Other people in forum are complaining about this and either killing the process or just uninstalling Norton completely. For example see: