Norton Engine Fallback Update?

Running Dell XPS 720, tonight on this PC I got the above named update which required a reboot. Now my PC is slower than ever. A full scan went on forever.

 

How, what and where can I find information about this update and what is it for?

 

If it matters, I'm running NIS2009 16.5.0.135.

 

 

Jim

 

Who thinks controlled rollouts should be done during testing with beta users and not to the public.