As your Samsung phone is running with Android OS, which is vulnerable to virus and malware and hackers. It need protection 24/7 from a security point of view. Hence McAfee as a efficient security program run's 24/7 in your device to do background scan and protect and secure your data and device from threats and Malware.
However I understand your concern on battery life. I will have this checked with my development team. Meantime, i would prefer to do a clean re-installation of McAfee security program and observe the battery life and please keep us posted.
If you have any concerns, feel free to reply to the post or contact our support team using the link below.