I had the exact same issue couple of days back when I installed my 1060(my previous gpu which was a 1050ti which died) and when I launched games they were very laggy. And the fps was less compared to 1050ti. The GPU was sitting at 20-50% usage while my CPU was at 100% all the time. I tried DDU and installed drivers again and even installed old driver but none of that helped.
I also noticed slightly higher CPU temps(80 degree celcius) so i applied new thermal paste and along with that a clean installation of windows fixed my issue. I highly recommend a fresh installation of windows, i believe that is what fixed the issue for me. Do check your CPU temps if you haven't used your PC in a while.