As it stands now like iOS its very difficult for malicious software to move around MacOS in a way that has anything more than an annoying result. That doesn't mean it will always be that way but for the time being MacOS is fairly secure assuming you practice safe browsing habits and don't fall for a phishing scheme.
Anti virus software like Norton has to ask you the user to remove the barriers that prevent it from even looking. The end results is what sounds more like an insurance plan.....
Than a piece of software that can combat malicious software. Don't give it too much access though because it will hurt performance according to Apple.
If a Time Machine backup on your Mac is slow, try these suggestions.
support.apple.com
Wouldn't be Norton if it wasn't slowing your system down I guess.
I'm not saying you shouldn't use an AV or anti malware software (I personally use Malwarebytz) but sprinkling a lousy AV program on top of what Apple implements is a bit pointless. I understand why but cracking the security gate to let fat ass Norton in makes me cringe due to my experience with him in Windows especially knowing his protection is mostly reactive (LifeLock and "virus protection promise") vs proactive.
Apples has a huge advantage when it comes to security because they make the hardware and software. Believe it or not combatting and quarantining a virus that is already on the system you are trying to protect is not a preferred solutions, its an unfortunate requirement.
Apple utilizes their biometrics, cryptography engine, proprietary SSD's, T2/Secure enclave, all of Intels good tech like MDM, SMM and cripples their bad tech like ME and OROM being disabled due to the potential for attack. Boot Rom is psychically burned into the T2 chip so it can not be manipulated which verifies EFI before its finally handed off to the Intel CPU. All your data is encrypted tight and core functions are supervised by Apples T2 SoC. The T2 remains completely isolated from the kernel and CPU to maintain system keys and cryptography functions integrity. Even the microphone is physically disconnected when the lid is closed on the MacBooks making it impossible for malware to access the mic for eavesdropping.
For software they have your standard countermeasures like EFIcheck to detect rootkits, XProtect AV software, MRT - malware removal tools, Keychain, etc. Plus they use a bit more unique protection software like app sandboxing, gatekeeper - check software signing, SIP - System integrity protection which makes system code read only.
Apple outlines this stuff thoroughly on their webpage. Norton says they have a "virus protection promise"....that means nothing...marketing for those that trust corporate promises.