This applies to Windows 10 x64 on my ASUS ROG Maximus VIII Extreme system with Intel Core i7 6700K CPU, 32 gbytes Rip Jaws DDR4 RAM and dual Samsung 850 Pro SSDs and also my MS Surface Pro tablet with Windows 10 x64 and internal SSD.
When performing a full or custom scan, the NS scanner pounds the CPU continuously at 90-100% CPU utilization and temperatures up to 79 C on all cores. On these systems, the use of the system is very slow for anything else other than the NS scan.
I have done all the exercises of uninstalling NS with the removal tool, etc., and then re-installing, updating to no avail.