McAfee Site Advisor is software which integrates with Internet Explorer and FireFox. It provides two features which are the safety level of the website the user is visiting and when searching in search engines, a safe rating is displayed showing whether to click on the result or not.
Non-system processes like mcsacore.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that your registry has suffered fragmentation and accumulated invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues