Windows 10 defender firewall MpsSvc and Internet Sharing Services (ICS) consuming high CPU usage

I had the same issue on Windows 10, Firewall + ICS service constantly taking up 10% of CPU time.

I don't have Windows Defender enabled so couldn't follow the top answer's instructions. Instead:

Click Start and type wf.msc

Click Restore Default Policy

I'm sure it has the same effect as the other answer

I was having the same issue but I do use Windows Defender's firewall. Resetting the firewall defaults worked for me.

I found the fix at https://answers.microsoft.com/en-us/windows/forum/windows_10-other_settings/since-windows-10-fall-creators-update-1709/d03167cc-92e7-4d13-94ce-84fda7b0f94f

Reset Windows Defender Firewall:

Settings -> Update and Security -> Windows Defender -> Open Windows Defender Security Center -> Firewall and Network Protection -> Restore Firewall default settings > Click the button to restore the defaults

Or

Use the Windows Firewall repair tool:

https://support.microsoft.com/en-us/help/17613/automatically-diagnose-and-fix-problems-with-windows-firewall

In Services Manager, change the Startup Type of the Internet Connection Sharing (ICS) service from "Automatic" to "Manual". In Task Manager, kill the ICS SVCHOST instance that hogs 10% CPU. This will disable ICS but it will stop the CPU waste.

In previous answers I tried to "provide details" (as per this website guidelines) but the moderators did not agree that those details were constructive, so they deleted them. If you're interested, write to me in private, I guess.