NVIDIA's latest Game Ready drivers, which come in at version 375.86, are apparently causing performance problems for some. According to a number of posters on NVIDIA's forums and on NeoGaf (via PCGamer) have reported various performance issues in games, and an NVIDIA representative has now confirmed that the problem stems from an issue causing the memory clock speed on some factory overclocked cards to be stuck at 810Mhz.

NVIDIA's latest game ready driver is hindering memory performance on some cards

From NVIDIA:

Just a quick update on the memory clock speed stuck at 810MHz issue. This issue seems to affect some factory overclocked GeForce GTX 1060/1070/1080 cards. We have reproduced this issue and identified the root cause. A hotfix driver will be made available as soon as a fix has been confirmed.

There's no given timeline on when to expect a hotfix, but if you own one of the named cards, it's likely you'll run into some performance issues until an update can be rolled out. In the meantime, if you haven't installed the drivers, it might be a good idea to wait until this problem is fixed.