Using Silent Mode to Prevent Hard Drive Usage

I have NIS 2015 installed. It is constantly making the hard drive run. I run for expended periods of time. During this time it was choking my computer, making it run extremely slowly. The hard drive usage is evident in the screen shot of the Task Manager I have attached.

I finally tried putting NIS into silent mode and the hard drive thrashing finally stopped and the computer is running fine. I believe the computer is still protected in Silent Mode.

If this is correct, is there any problem with running Silent Mode full time to get back my computer performance?

Thanks for any thoughts.