A proper idle CPU reading means nothing at all running except Windows and it's own background stuff and basic things like an antivirus. So if it's more like 1-2% with no Chrome and such that's fine. In the startup tab in task manager anything that's not critical is safe to disable. Keep anything related to McAfee, and keep Onedrive if you use it or expect you might (though if you don't even sign in with a Microsoft cloud account, might as well disable it) and keep Windows defender. Dell's pre-loaded stuff can be disabled or outright uninstalled if you see no use for it.